WO2018181455A1 - Methods for producing lactobacillus starter and yoghurt - Google Patents

Methods for producing lactobacillus starter and yoghurt Download PDF

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Publication number
WO2018181455A1
WO2018181455A1 PCT/JP2018/012704 JP2018012704W WO2018181455A1 WO 2018181455 A1 WO2018181455 A1 WO 2018181455A1 JP 2018012704 W JP2018012704 W JP 2018012704W WO 2018181455 A1 WO2018181455 A1 WO 2018181455A1
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Prior art keywords
lactic acid
medium
acid bacteria
bacteria
milk
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PCT/JP2018/012704
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French (fr)
Japanese (ja)
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武文 市村
和典 柏木
智子 市場
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株式会社明治
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Priority to JP2019509962A priority Critical patent/JP7232177B2/en
Publication of WO2018181455A1 publication Critical patent/WO2018181455A1/en

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    • A—HUMAN NECESSITIES
    • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
    • A23C—DAIRY PRODUCTS, e.g. MILK, BUTTER OR CHEESE; MILK OR CHEESE SUBSTITUTES; MAKING THEREOF
    • A23C9/00—Milk preparations; Milk powder or milk powder preparations
    • A23C9/12—Fermented milk preparations; Treatment using microorganisms or enzymes
    • A23C9/123—Fermented milk preparations; Treatment using microorganisms or enzymes using only microorganisms of the genus lactobacteriaceae; Yoghurt
    • A—HUMAN NECESSITIES
    • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
    • A23C—DAIRY PRODUCTS, e.g. MILK, BUTTER OR CHEESE; MILK OR CHEESE SUBSTITUTES; MAKING THEREOF
    • A23C9/00—Milk preparations; Milk powder or milk powder preparations
    • A23C9/12—Fermented milk preparations; Treatment using microorganisms or enzymes
    • A23C9/127—Fermented milk preparations; Treatment using microorganisms or enzymes using microorganisms of the genus lactobacteriaceae and other microorganisms or enzymes, e.g. kefir, koumiss
    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
    • C12N1/00—Microorganisms, e.g. protozoa; Compositions thereof; Processes of propagating, maintaining or preserving microorganisms or compositions thereof; Processes of preparing or isolating a composition containing a microorganism; Culture media therefor
    • C12N1/20—Bacteria; Culture media therefor
    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
    • C12N9/00—Enzymes; Proenzymes; Compositions thereof; Processes for preparing, activating, inhibiting, separating or purifying enzymes
    • C12N9/14—Hydrolases (3)
    • C12N9/24—Hydrolases (3) acting on glycosyl compounds (3.2)

Definitions

  • the present invention relates to a method for producing a lactic acid bacteria starter and a method for producing fermented milk using the lactic acid bacteria starter.
  • fermented milk when producing fermented milk, a mother starter is cultured in a medium for lactic acid bacteria and subjected to intermediate fermentation to obtain a lactic acid bacteria starter used for fermentation of raw milk. And fermented milk will be manufactured by inoculating raw material milk (yogurt mix) with the lactic-acid-bacteria starter obtained here, and fermenting by hold
  • lactic acid bacteria starters are cultured over several stages, and then transferred from the original mother starter over several generations, and scaled up while activating the lactic acid bacteria starters at each stage. Sometimes.
  • yogurt contains a predetermined amount of functional polysaccharide (EPS) produced by Bulgarian bacteria.
  • EPS functional polysaccharide
  • Patent Document 1 discloses a method for producing low-fat yogurt in which oleic acid or the like is added to raw milk. According to Patent Document 1, it is proposed that the survival of lactic acid bacteria in low-fat yogurt can be improved by using oleic acid or the like.
  • Patent Document 2 discloses a fermented food production method in which guava leaf extract is added to raw milk. According to Patent Document 2, it is proposed that the use of guava leaf extract can improve the survival of lactic acid bacteria in fermented foods because it functions as a survival improver for lactic acid bacteria and a growth promoter for lactic acid bacteria. ing.
  • Patent Document 3 discloses a method for producing fermented foods in which gum arabic is added to raw milk. According to Patent Document 3, it is proposed that the survival rate of bifidobacteria during storage of fermented food can be increased by using gum arabic.
  • an object of the present invention is to provide a technique capable of promoting the growth of Bulgarian bacteria contained in fermented milk.
  • an object of the present invention is to relatively promote the growth of Bulgaria bacteria and relatively suppress the growth of Thermophilus bacteria in fermented milk containing Bulgaria bacteria and Thermophilus bacteria.
  • the inventors of the present invention have conducted intensive studies on means for solving the conventional problems. As a result, when producing a lactic acid bacteria starter to be used for fermentation of raw milk, lactose decomposition is performed on the medium for the lactic acid bacteria starter. In the fermented milk obtained using such a lactic acid bacteria starter, the Bulgarian bacteria were found to increase relatively. Then, the present inventors have conceived that, based on the above findings, the growth of Bulgarian bacteria contained in fermented milk can be promoted, and the present invention has been completed. Specifically, the present invention has the following steps.
  • the first aspect of the present invention relates to a method for producing a lactic acid bacteria starter.
  • the lactic acid bacteria starter is basically used to ferment raw milk to obtain fermented milk.
  • the lactic acid bacteria starter obtained by the present invention in addition to directly inoculating the raw milk with the lactic acid bacteria starter obtained by the present invention, the lactic acid bacteria starter obtained by the present invention is further cultured in the medium at least once, It also includes inoculating raw milk with the lactic acid bacteria starter of the next generation after the culture.
  • the method for producing a lactic acid bacteria starter according to the present invention includes a medium preparation process, a medium sterilization process, a lactic acid bacteria inoculation process, a medium fermentation process (culture process), and a lactose decomposition process.
  • the medium preparation step is a step of preparing a medium containing milk components.
  • the medium sterilization step is a step of sterilizing the medium by heating, for example.
  • the lactic acid bacteria inoculation step is a step of inoculating a sterilized medium with lactic acid bacteria containing Bulgarian bacteria.
  • the medium fermentation step is a step of fermenting the medium after inoculation with lactic acid bacteria.
  • the lactose decomposition step is a step of decomposing lactose in the medium.
  • the lactose decomposition step is a step in which lactose in the medium is decomposed before the medium fermentation step.
  • the lactose decomposition step may be performed before the medium sterilization step.
  • the lactose decomposition step may be performed after the medium sterilization step and before the lactic acid bacteria inoculation step.
  • the lactose decomposition step may be a step of degrading lactose in the medium by adding lactose decomposing enzyme simultaneously with lactic acid bacteria to the medium.
  • the lactose decomposition step is a step of degrading lactose in the medium by adding lactose-degrading enzyme to the medium before raising the temperature of the medium after inoculation with lactic acid bacteria to the fermentation temperature range (for example, 35 ° C. to 50 ° C.). There may be.
  • the lactic acid bacterium preferably further contains Thermophilus bacterium in addition to Bulgaria bacterium.
  • the lactose decomposition step is preferably a step in which the lactose decomposition rate in the medium is 70% or more. Specifically, it is preferable that the lactose decomposition rate of the medium becomes 70% or more at least when the medium reaches the fermentation temperature range (for example, 35 ° C. to 50 ° C.). For example, when the lactose decomposition step is performed before the medium sterilization step, the lactose decomposition rate of the medium is preferably 70% or more when the medium is sterilized.
  • the lactose decomposition rate of the medium is preferably 70% or more when the medium is inoculated with lactic acid bacteria.
  • lactic acid bacterium starter when producing a lactic acid bacterium starter, lactose decomposition is performed on a medium for the lactic acid bacterium starter, and fermented milk is produced using the lactic acid bacterium starter.
  • the number of bacteria can be increased.
  • fermented milk containing Bulgaria and thermophilus bacteria by utilizing the lactic acid bacteria starter produced according to the present invention, the growth of Bulgaria bacteria is relatively accelerated, and thermophilus is produced. The growth of bacteria can be relatively suppressed.
  • the lactic acid bacteria starter containing Bulgarian bacteria and thermophilus bacteria it was the technical common sense that the thermophilus bacteria became more dominant as the passage (planting of the bacteria) was repeated, but according to the present invention, the lactic acid bacteria starter Fermented milk has a higher proportion of Bulgarian bacteria. For this reason, it is presumed that the activity (proliferation ability) of the Bulgarian bacteria contained therein is strengthened by carrying out lactose decomposition during the production of the lactic acid bacteria starter.
  • the present invention is characterized in that lactose decomposition is not performed on the raw material milk that is the basis of fermented milk, but is performed on the medium for the lactic acid bacteria starter. However, the present invention does not exclude performing lactose decomposition on raw milk.
  • the second aspect of the present invention relates to a method for producing fermented milk.
  • the method for producing fermented milk according to the present invention utilizes the lactic acid bacteria starter obtained by the method for producing a lactic acid bacteria starter according to the first aspect described above for the production of fermented milk.
  • the lactic acid bacteria starter may be directly inoculated into the raw milk, or the lactic acid bacteria starter is further cultured once or more in the medium, and the lactic acid bacteria starter from the next generation onwards after the cultivation is used as the raw milk. You may inoculate.
  • the growth of Bulgarian bacteria contained in fermented milk can be promoted.
  • the proliferation of a Bulgaria bacterium can be accelerated
  • FIG. 1 is a flowchart showing an example of each step included in the method for producing a lactic acid bacteria starter and the method for producing fermented milk according to the present invention.
  • FIG. 1 shows each step (S1 to S5) for producing a lactic acid bacteria starter and each step (S6 to S9) for producing fermented milk. Below, it demonstrates according to the flowchart shown in FIG.
  • the method for producing a lactic acid bacteria starter is a method for producing a lactic acid bacteria starter used for fermentation of raw material milk by culturing lactic acid bacteria serving as inoculums in a medium and subjecting them to intermediate fermentation.
  • “Lactic acid bacteria starter” includes those prepared by culturing a certain lactic acid bacteria in a medium (solution) and intermediate fermentation.
  • the lactic acid bacteria starter basically includes lactic acid bacteria and a medium solution in which the lactic acid bacteria are cultured as components.
  • the lactic acid bacteria starter includes the next generation and beyond, in which the lactic acid bacteria starter is further inoculated into another medium and scaled up. included.
  • the method for producing a lactic acid bacteria starter includes a medium preparation process (S1), a medium sterilization process (S2), a lactic acid bacteria inoculation process (S3), a culture process (medium fermentation process) (S4), and lactose decomposition. Including a step (S5).
  • the lactose decomposition step (S5) is performed between the first lactose decomposition step (S5-1) performed between the medium preparation step and the medium sterilization step, and between the medium sterilization step and the lactic acid bacteria inoculation step.
  • the first to third lactose decomposition steps may be performed at least one or all of them.
  • the medium preparation step (S1) is a step of preparing a medium for inoculating lactic acid bacteria.
  • the medium is a solution for culturing lactic acid bacteria.
  • the number of lactic acid bacteria can be increased by inoculating the medium with lactic acid bacteria and culturing the lactic acid bacteria in the medium.
  • the medium contains non-fat milk solids (SNF) of 6% by weight or more, preferably 8% by weight or more, more preferably 9% by weight or more.
  • SNF non-fat milk solids
  • the upper limit of the non-fat milk solid content of the medium is not particularly limited, it is preferably, for example, 30% by weight or less or 25% by weight or less.
  • the non-fat milk solid content is preferably derived from skim milk powder.
  • skim milk powder about 95% of skim milk powder is nonfat milk solid content, and most of the remainder is moisture.
  • a culture medium consists only of non-fat milk solid content and a water
  • the sterilization step (S2) is a step of sterilizing the medium prepared in the medium preparation step, for example, by heating.
  • the heating temperature and the heating time may be adjusted so as to sterilize the bacteria in the medium.
  • the medium is preferably heated to 80 ° C. or higher, 90 ° C. or higher, 95 ° C. or higher, or 100 ° C. or higher.
  • a known method can be used for the heat sterilization.
  • heat treatment may be performed with a plate heat exchanger, tube heat exchanger, steam injection heating device, steam infusion heating device, energizing heating device, etc., and heating is performed with a jacketed tank. Processing may be performed.
  • the sterilization of the medium is not limited to heating, and can be performed by a known method such as ultraviolet irradiation.
  • the medium when the medium is sterilized by heating, it is preferable to cool the medium at a high temperature to a temperature range (culture temperature range) suitable for culturing lactic acid bacteria before the lactic acid bacteria addition step.
  • the culture temperature range means a temperature at which microorganisms (such as lactic acid bacteria) are activated to promote the growth of the microorganisms.
  • the culture temperature range of lactic acid bacteria is generally 30 to 60 ° C.
  • the lactic acid bacteria inoculation step (S3) is a step of inoculating (adding) lactic acid bacteria to the medium in the culture temperature range.
  • lactic acid bacteria may be inoculated after the medium has been lowered to a predetermined temperature after heat sterilization, or lactic acid bacteria may be inoculated while the medium has been lowered to a predetermined temperature after heat sterilization.
  • freeze-concentrated bacteria, frozen pellets, freeze-dried powders, and the like can be used.
  • lactic acid bacteria inoculation step lactic acid bacteria are preferably added at 0.05% by weight or more with respect to the medium. Specifically, lactic acid bacteria may be added at 0.05 to 10% by weight or 0.1 to 5% by weight with respect to the medium.
  • the freeze-concentrated bacteria for example, those described in Japanese Patent No. 5963389 can be used.
  • lactic acid bacteria include Bulgarian bacteria. “Bulgaria” is L. bulgaricus. Moreover, it is preferable that lactic acid bacteria contain Thermophilus bacteria in addition to Bulgarian bacteria. "Thermophilus” is Streptococcus thermophilus (S. thermophilus).
  • the lactic acid bacteria may include known lactic acid bacteria in addition to Bulgarian bacteria and Thermophilus bacteria. Examples of known lactic acid bacteria include gasseri (L. gasseri), lactis (L. lactis), cremiris (L. There are bacteria such as Bifidobacterium.
  • the culturing step (S4) is a step of cultivating lactic acid bacteria in a medium and growing the lactic acid bacteria.
  • the cultivation of lactic acid bacteria is preferably terminated with the acidity of the medium as a guide.
  • the upper limit of the culturing time for lactic acid bacteria is not particularly limited.
  • the culture may be terminated when fermentation of the medium proceeds and the acidity of the medium reaches a predetermined value.
  • the acidity at the end of the culture is preferably set to 0.7%, 0.75%, or 0.8%, and may be set to a range of 0.7 to 1.2%.
  • the acidity (lactic acidity) of the medium is measured according to the “Testing Method for Component Standards of Milk” in the Ministerial Ordinance of Milk. Specifically, 10 mL of ion exchange water not containing carbon dioxide gas is added to 10 g of the sample at 10 mL, and then a phenolphthalein solution is added at 0.5 mL as an indicator. While adding sodium hydroxide solution (0.1 mol / L), titration was performed up to the point where the faint red color did not disappear, and the content of lactic acid per 100 g of the sample was determined from the titration of the sodium hydroxide solution. , Acidity (lactic acidity). The phenolphthalein solution is prepared by dissolving 1 g of phenolphthalein in an ethanol solution (50%) and filling up to 100 mL.
  • the temperature of the medium is preferably maintained in the fermentation temperature range of 35 ° C. or higher.
  • the temperature of the medium is preferably maintained at 35 to 55 ° C., more preferably 37 to 52 ° C., and further preferably 40 to 50 ° C.
  • cultivation time of a lactic acid bacteria starter is 3 hours or more, 5 hours or more, or 7 hours or more.
  • the culture medium that has been cultured (that is, the medium that has reached a predetermined acidity) is cooled to a temperature at which the growth of lactic acid bacteria is suppressed.
  • the medium is preferably cooled to 0 to 20 ° C, 3 to 15 ° C, or 5 to 10 ° C.
  • the cooling process may be performed by a plate heat exchanger, a tube heat exchanger, or a vacuum (reduced pressure) evaporative cooler, or by a jacketed tank.
  • the lactose decomposition step (S5) is a step of decomposing lactose (lactose) contained in the medium.
  • the lactose decomposition step is preferably performed by adding lactose-degrading enzyme (such as lactase) to the medium.
  • lactose-degrading enzymes are enzymes classified as glycosyl hydrolases based on amino acid sequence homology, and hydrolyze lactose into galactose and glucose. Examples of lactose-degrading enzymes include those derived from bacteria or yeast.
  • the optimum pH for activity is 6.3 to 7.5, and the deactivation pH is 6.0 to 4.0.
  • Lactose decomposing enzyme the thing derived from Kluyveromyces actLactis or the thing derived from Kluyveromyces fragilis (Kluyveromyces Fragilis) is preferable.
  • Lactose degrading enzymes derived from Kluyveromyces lactis include those derived from Kluyveromyces lactis as well as Kluyveromyces lactis itself.
  • Lactose-degrading enzymes are commercially available, and examples of commercially available lactose-degrading enzymes include GODO-YNL (manufactured by Godo Shusei Co., Ltd.), lactase F (manufactured by Amano Enzyme), and lactres L-3 (manufactured by Daiwa Kasei Co., Ltd.) And Lactores L-10 (manufactured by Daiwa Kasei Co., Ltd.).
  • GODO-YNL manufactured by Godo Shusei Co., Ltd.
  • lactase F manufactured by Amano Enzyme
  • lactres L-3 manufactured by Daiwa Kasei Co., Ltd.
  • Lactores L-10 manufactured by Daiwa Kasei Co., Ltd.
  • the lactose decomposition step is performed between the first lactose decomposition step (S5-1) performed between the medium preparation step and the medium sterilization step, and between the medium sterilization step and the lactic acid bacteria inoculation step.
  • the first to third lactose decomposition steps may be performed at least one or all of them.
  • the lactose decomposition rate of the medium at the start of heat sterilization is preferably 70% or more, more preferably 80% or more, and particularly preferably 90% or more.
  • the medium is subjected to lactose decomposition before the medium is inoculated with lactic acid bacteria.
  • the lactose decomposition rate of the medium at the time of inoculation with lactic acid bacteria is preferably 70% or more, more preferably 80% or more, and particularly preferably 90% or more.
  • lactose decomposition enzyme is added to the medium at the same time as lactic acid bacteria, or lactose decomposition of the medium is performed before the temperature of the medium after inoculation with lactic acid bacteria is raised to the fermentation temperature range.
  • the lactic acid bacteria may be inoculated into the medium before the medium starts to be heated, or may be inoculated into the medium while the medium is being heated.
  • the lactose decomposition may be completed before the medium starts to be heated, or may be advanced while the medium is being heated.
  • the lactose decomposition rate of the medium is preferably 70% or more, more preferably 80% or more, and 90% or more. Is particularly preferred.
  • the time when the medium reaches the fermentation temperature range is almost equal to the time when the thermophilus starts to grow.
  • the point in time when Thermophilus begins to grow can be rephrased as the point in the logarithmic growth phase.
  • the “lactose content” can be measured by the arginine fluorescence method (BUNSEKI KAGAKA, 32, E207, 1983) by high performance liquid chromatography.
  • the “glucose concentration in the lactose-decomposed medium solution” can be measured by a measuring method using a kit that can measure the glucose concentration in a short period of time (for example, Medisafe Mini, etc. of TERUMO Co., Ltd.).
  • first to third lactose decomposition steps considering the production efficiency of the lactic acid bacteria starter, it is particularly preferable to perform the first lactose decomposition step (S5-1) or the second lactose decomposition step (S5-2). preferable.
  • the third lactose decomposition step (S5-2) it is necessary to finish the lactose decomposition in a short period of “induction period” from the inoculation of lactic acid bacteria to the start of growth. Is required.
  • lactose is inoculated after lactose decomposition is completed, and the time for lactose decomposition is not particularly limited.
  • Lactose degradation rate can be achieved.
  • the amount of lactose-degrading enzyme added to the medium is about 10% to 20% as compared with the third lactose decomposition step.
  • it is the 1st and 2nd lactose decomposition process it is possible to achieve a desired lactose decomposition rate more reliably with a small amount of lactose decomposing enzyme.
  • a lactic acid bacteria starter can be produced by the above steps (S1 to S5).
  • the lactic acid bacteria starter can be used for the production of fermented milk described later.
  • the lactic acid bacteria starter includes lactic acid bacteria and a medium component in which the lactic acid bacteria are cultured as constituent elements.
  • the lactic acid bacteria starter manufactured by the method including the lactose decomposition step relatively promotes the growth of Bulgaria bacteria and relatively suppresses the growth of Thermophilus bacteria.
  • the number of Bulgarian bacteria was 60% of the number of Thermofilus bacteria (100%). % Or more, 65% or more, or 70% or more, more preferably 100% or more, and particularly preferably 110% or more, or 120% or more.
  • the lactic acid bacteria starter contains an overwhelming number of thermophilus bacteria, and the number of Bulgarian bacteria is larger than the number of thermophilus bacteria.
  • the number of Bulgarian bacteria relative to Thermophilus can be set to 60% or more. For this reason, according to the present invention, it is possible to relatively promote the growth of Bulgarian bacteria and relatively suppress the growth of Thermophilus bacteria.
  • the number of lactic acid bacteria (Bulgaria and Thermophilus) contained in the lactic acid bacteria starter is finally measured when the medium that has reached a predetermined acidity is cooled and the temperature of the medium reaches 10 ° C. To do.
  • ⁇ be the numerical value of the ratio of the number of Bulgarian bacteria to the number of Thermophilus bacteria contained in the lactic acid bacteria inoculated into the medium (the number of Bulgarian bacteria / the number of Thermofilus bacteria). Further, ⁇ is the ratio of the number of Bulgarian bacteria to the number of Thermophilus bacteria contained in the finally obtained lactic acid bacteria starter (the number of Bulgarian bacteria / the number of Thermophilus bacteria).
  • the numerical value of ⁇ / ⁇ is preferably 1.1 or more. Further, it is more preferable that the numerical value of ⁇ / ⁇ is 1.2 or more, 1.5 or more, 2.0 or more, 2.5 or more, or 3.0 or more.
  • the upper limit of the numerical value of ⁇ / ⁇ is not particularly limited, but may be 20.0, for example.
  • the ratio of the number of Bulgarian bacteria to the number of Thermophilus bacteria can be dramatically improved. That is, according to the present invention, it is possible to relatively promote the growth of Bulgarian bacteria and relatively suppress the growth of Thermophilus bacteria.
  • fermented milk produced according to the present invention is yogurt.
  • the yogurt may be a plain type, a hard type, a soft type, or a drink type.
  • examples of fermented milk include frozen yogurt and cheese materials.
  • the fermented milk may be any of “fermented milk”, “dairy lactic acid bacteria beverage”, “lactic acid bacteria beverage” and the like defined by a Japanese ordinance of milk.
  • the method for producing fermented milk is a method for producing fermented milk by fermenting raw material milk using the lactic acid bacteria starter obtained through each step (S1 to S5).
  • the method for producing fermented milk includes a raw material milk preparation step (S6), a raw material milk sterilization step (S7), a lactic acid bacteria starter inoculation step (S8), and a fermentation step (S9).
  • the raw material milk preparation step (S6) is a step of preparing raw material milk that is a source of fermented milk.
  • Raw milk is also called yogurt base or yogurt mix.
  • known milk can be used as raw material milk.
  • raw material milk may consist of raw milk only (raw milk is 100%).
  • the raw milk may be prepared by mixing raw milk with skim milk powder, cream, water, and the like.
  • raw milk is sterilized milk, whole milk, skim milk, whole fat concentrated milk, whole fat concentrated milk, whole fat milk powder, butter milk, salted butter, unsalted butter, whey, whey powder, Whey protein concentrate (WPC), whey protein isolate (WPI), ⁇ -La (alpha-lactalbumin), ⁇ -Lg (beta-lactoglobulin), prepared by mixing (adding) lactose, etc.
  • WPC Whey protein concentrate
  • WPI whey protein isolate
  • ⁇ -La alpha-lactalbumin
  • ⁇ -Lg beta-lactoglobulin
  • the raw material milk preparation process it is preferable to atomize (pulverize) fat globules and the like contained in the raw material milk by homogenizing the raw material milk. That is, by homogenizing the raw material milk, the fat content of the raw material milk and the fermented milk can be prevented from separating and rising during the manufacturing process and after the manufacturing of the fermented milk.
  • the raw material milk sterilization step (S7) is a step of sterilizing the raw material milk prepared in the raw material milk preparation step, for example, by heating.
  • the heating temperature and the heating time may be adjusted so as to sterilize the germs of the raw material milk.
  • the raw milk is preferably heated to 80 ° C. or higher, preferably 90 ° C. or higher.
  • a known method can be used for the heat treatment.
  • heat treatment such as high temperature short time sterilization treatment (HTST) may be performed.
  • HTST high temperature short time sterilization treatment
  • UHT ultra high temperature sterilization
  • the high temperature short time sterilization process may be a process in which the raw milk is heated to 80 ° C. to 100 ° C. for about 3 minutes to 15 minutes. ) May be a process of heating to 110 ° C. to 150 ° C. for about 1 to 30 seconds.
  • the raw material milk that has become hot is cooled to a temperature range suitable for fermentation (fermentation temperature range).
  • the fermentation temperature range is generally 30 to 60 ° C.
  • the raw material milk that has been heated to high temperature after heat sterilization is preferably cooled to a fermentation temperature range of 35 to 55 ° C., for example, and more preferably 40 to 50 ° C.
  • the lactic acid bacteria starter inoculation step (S8) is a step of inoculating (adding) the lactic acid bacteria starter obtained through the above-described lactic acid bacteria starter production method (S1 to S5) to the medium cooled to the fermentation temperature range.
  • the lactic acid bacteria starter may be inoculated after the raw milk has been lowered to a predetermined temperature after heat sterilization, or the lactic acid bacteria starter is added while the raw milk has been lowered to the predetermined temperature after the heat sterilization step. You may inoculate.
  • the lactic acid bacteria starter is preferably added at 0.1% by weight or more with respect to the raw milk. Specifically, the lactic acid bacteria starter may be added at 0.1 to 15% by weight, 0.5 to 10% by weight, or 1 to 5% by weight with respect to the raw material milk.
  • the fermentation step (S9) is a step of fermenting raw material milk with a lactic acid bacteria starter.
  • the raw milk inoculated with the lactic acid bacteria starter is fermented while being kept in a fermentation temperature range (for example, 30 to 60 ° C.) to obtain fermented milk.
  • a known method can be used for the fermentation step.
  • the fermentation process may be performed in a fermentation chamber or the like, and the fermentation process may be performed in a tank with a jacket.
  • the post-fermentation process may be performed when the yogurt is a plain type or a hard type, and the pre-fermentation process may be performed when the yogurt is a soft type or a drink type.
  • the fermentation process may be a process in which the temperature in the fermentation chamber (fermentation temperature) is maintained at about 30 ° C. to 60 ° C. and the raw material milk is fermented in the fermentation chamber, or in a jacketed tank
  • the temperature (fermentation temperature) may be maintained at 30 to 60 ° C.
  • the raw milk may be fermented in the tank.
  • the conditions for fermenting the raw milk may be adjusted as appropriate, such as the fermentation temperature and the fermentation time, in consideration of the type and quantity of the raw milk and lactic acid bacteria, the flavor and texture of the fermented milk.
  • the raw milk is maintained in the fermentation temperature range for 1 hour or more.
  • the period for holding the raw milk (fermentation time) is preferably 1 hour to 12 hours, more preferably 2 hours to 8 hours, and more preferably 3 hours to 5 hours. Further preferred.
  • the conditions for fermenting raw milk may be adjusted as appropriate by considering the type and quantity of raw milk and lactic acid bacteria, the flavor and texture of fermented milk, and the like. Specifically, in the fermentation process, it is preferable that the lactic acidity of the fermented milk reaches 0.7% or more, and it is particularly preferable that the lactic acidity of the fermented milk reaches 0.8% or more. .
  • the acidity of the raw milk (lactic acidity) can be measured according to the “Testing Method for Component Standards of Milk” in the Ministerial Ordinance of Milk, similar to the acidity of the medium described above.
  • the fermentation process may be either post-fermentation treatment or pre-fermentation treatment.
  • this raw material milk is fermented.
  • fermented milk (fermented milk) that is an intermediate product obtained by fermenting (sealed) a container filled with raw milk containing lactic acid bacteria starter in a fermentation chamber. Card) is cooled in a re-cooling step to be described later, and fermented milk (set type yogurt, plain type yogurt) as a final product may be obtained.
  • raw material milk is fermented before filling raw material milk into the container for actually selling as a product.
  • the fermented milk (fermented milk card), which is the intermediate product, is fermented by leaving a jacketed tank filled with raw material milk, etc. Then, after cooling in the re-cooling process described later, and after mixing the pulp, vegetables, fruit juice, vegetable juice, jam, sauce, preparation, etc., it is filled into a (sealed) container and the final product What is necessary is just to obtain fermented milk (soft type yogurt, drink type yogurt).
  • the production amount of extracellular polysaccharide (EPS amount) in fermented milk is 3.0 mg / 100 g or more, 3.5 mg / 100 g or more, 4.0 mg. / 100 g or more, 4.5 mg / 100 g or more, or 5.0 mg / 100 g or more is preferable.
  • the upper limit of the EPS amount is not particularly limited, but is 10.0 mg / 100 g, for example. That is, according to the present invention, the amount of EPS in fermented milk can also be increased efficiently.
  • the fermented milk is cooled.
  • the progress of fermentation is suppressed by cooling fermented milk.
  • the fermented milk is cooled to a temperature lower than the fermentation temperature range (for example, 30 to 60 ° C.).
  • the fermented milk is preferably cooled to 15 ° C. or lower.
  • the fermented milk is preferably cooled to 1 to 15 ° C, more preferably 3 to 12 ° C, and even more preferably 5 to 10 ° C.
  • by cooling the fermented milk to a temperature suitable for edible use it is possible to suppress or prevent changes in flavor (such as acidity), texture (such as touch of the tongue), and physical properties (such as hardness) of the fermented milk.
  • the number of Bulgarian bacteria contained in the fermented milk can be relatively increased.
  • the number of Bulgarian bacteria was 60% of the number of Thermophilus bacteria (100%). % Or more, 65% or more, or 70% or more, more preferably 100% or more, and particularly preferably 110% or more, or 120% or more.
  • the fermented milk contains an overwhelming number of thermophilus bacteria.
  • the number of Bulgarian bacteria is the same as that of thermophilus bacteria. It is about 20% at most with respect to the number of bacteria.
  • the number of Bulgarian bacteria relative to Thermophilus bacteria can be 60% or more. For this reason, according to the present invention, it is possible to relatively promote the growth of Bulgarian bacteria and relatively suppress the growth of Thermophilus bacteria.
  • the number of lactic acid bacteria (Bulgaria bacteria and Thermophilus bacteria) finally contained in fermented milk is determined by cooling fermented milk that has reached a predetermined acidity in the fermentation process, and when the temperature of fermented milk reaches 10 ° C. Measure with
  • the number of Bulgarian bacteria contained in fermented milk can be increased only by devising a method for producing a lactic acid bacteria starter.
  • Some Bulgarian bacteria produce functional polysaccharides. Therefore, if the lactic acid bacteria starter obtained according to the present invention is used, fermented milk without a miscellaneous taste containing a large amount of polysaccharides can be produced without using additives such as a growth promoter for lactic acid bacteria.
  • the present invention does not prohibit the use of additives such as growth promoters for lactic acid bacteria, but may additionally add growth promoters or the like to further increase the number of Bulgarian bacteria. Of course it is possible.
  • the addition amount of the growth promoter should be 0 to 1% by weight, 0 to 0.5% by weight, or 0 to 0.1% by weight with respect to the weight of the finally obtained fermented milk. Is preferred.
  • a typical example of the growth promoter is a pH buffer, and other examples include oleic acid described in Patent Document 1 and guava leaf extract described in Patent Document 2.
  • disassembly can also be performed with respect to raw material milk in the manufacturing process (S6-S9) of fermented milk. In that case, lactose decomposition may be performed at an appropriate timing after the raw material milk adjustment step (S6).
  • Lactose decomposition of medium before sterilization first lactose decomposition step>
  • Non-fat dry milk: 80 g and tap water: 720 g were mixed to prepare a medium.
  • the temperature of this medium was adjusted to 5 ° C., and lactose-degrading enzyme (GODO-YNL, Godo Sakesei Co., Ltd.) was added at 0.1% by weight.
  • lactose decomposition rate in the medium reached 100%, it was heated (sterilized) at 95 ° C. for 5 minutes and then cooled to 40 ° C.
  • lactic acid bacteria starter (Example 1).
  • the number of Bulgarian and Thermophilus bacteria contained in the lactic acid bacteria starter was measured when the temperature reached 10 ° C., they were 51.0 ⁇ 10 7 cfu / g and 71.0 ⁇ 10 7 cfu / g, respectively.
  • raw milk 800 g
  • skim milk powder 20 g
  • sugar 45 g
  • tap water 100 g
  • the raw milk is filled into a cup container (capacity: 100 g, made of plastic), and in the fermentation chamber (43 ° C.) Was allowed to stand and fermented until it reached 0.8%, and then cooled in a refrigerator (10 ° C. or lower) to produce a set-type yogurt (fermented milk).
  • Lactose decomposition of medium after sterilization second lactose decomposition step>
  • Non-fat dry milk: 80 g and tap water: 720 g were mixed to prepare a medium.
  • the medium was heated (sterilized) at 95 ° C. for 5 minutes, then cooled to 40 ° C., and lactose-degrading enzyme (GODO-YNL, Godo Sakesei Co., Ltd.) was added at 0.1% by weight. After the lactose decomposition rate in the medium reached 70% or more, lactic acid bacteria including Bulgarian bacteria and Thermophilus bacteria were inoculated at 0.15% by weight.
  • the medium was fermented in a fermentation chamber (40 ° C.) until the lactic acid acidity reached 0.75%, and then cooled in a refrigerator (10 ° C. or lower) to produce a lactic acid bacteria starter (Example 2).
  • a lactic acid bacteria starter (Example 2).
  • the number of Bulgarian bacteria and Thermophilus bacteria contained in the lactic acid bacteria starter was measured when the temperature reached 10 ° C., they were 58.5 ⁇ 10 7 cfu / g and 56.0 ⁇ 10 7 cfu / g, respectively.
  • raw milk 800 g
  • skim milk powder 20 g
  • sugar 45 g
  • tap water 100 g
  • raw milk heated (sterilized) at 95 ° C. for 5 minutes, and then cooled to 43 ° C.
  • lactic acid bacteria Example 2
  • the raw milk is filled into a cup container (capacity: 100 g, made of plastic), and the lactic acid acidity is increased in the fermentation chamber (43 ° C.).
  • a refrigerator 10 ° C. or lower
  • Lactose decomposition of the medium together with activated culture third lactose decomposition step>
  • Non-fat dry milk: 80 g and tap water: 720 g were mixed to prepare a medium.
  • the medium was heated (sterilized) at 95 ° C. for 5 minutes, then cooled to 40 ° C., and lactic acid bacteria including Bulgarian bacteria and Thermophilus bacteria were inoculated at 0.15% by weight.
  • lactose-degrading enzyme (GODO- 0.1% by weight of YNL, Godo Shusei Co., Ltd.) was added.
  • the medium was fermented in a fermentation chamber (40 ° C.) until the lactic acid acidity reached 0.75%, and then cooled in a refrigerator (10 ° C. or lower) to produce a lactic acid bacteria starter (Example 3).
  • a lactic acid bacteria starter (Example 3).
  • the number of Bulgarian and Thermophilus bacteria contained in the lactic acid bacteria starter was measured when the temperature reached 10 ° C., they were 63.0 ⁇ 10 7 cfu / g and 47.0 ⁇ 10 7 cfu / g, respectively.
  • raw milk 800 g
  • skim milk powder 20 g
  • sugar 45 g
  • tap water 100 g
  • raw milk heated (sterilized) at 95 ° C. for 5 minutes, and then cooled to 43 ° C.
  • the raw material milk is filled into a cup container (capacity: 100 g, made of plastic), and the lactic acid acidity is increased in the fermentation chamber (43 ° C.). After stationary fermentation until it reached 0.8%, it was cooled in a refrigerator (10 ° C. or lower) to produce a set-type yogurt.
  • ⁇ Comparative Example 1 Lactose is not degraded>
  • Non-fat dry milk: 80 g and tap water: 720 g were mixed to prepare a medium.
  • This medium was heated (sterilized) at 95 ° C. for 5 minutes, then cooled to 40 ° C., and inoculated with 0.15% by weight of lactic acid bacteria including Bulgarian bacteria and Thermophilus bacteria.
  • the medium was fermented in a fermentation chamber (40 ° C.) until the lactic acid acidity reached 0.75%, and then cooled in a refrigerator (10 ° C. or lower) to produce a lactic acid bacteria starter (Comparative Example 1). .
  • raw milk 800 g
  • skim milk powder 20 g
  • sugar 45 g
  • tap water 100 g
  • the raw milk is filled into a cup container (capacity: 100 g, made of plastic), and the lactic acid acidity in the fermentation chamber (43 ° C.) Was allowed to stand until it reached 0.8%, and then cooled in a refrigerator (10 ° C. or lower) to produce a set-type yogurt.
  • the ratio of Bulgarian bacteria to Thermophilus bacteria was about 71%.
  • the ratio of Bulgarian bacteria to Thermophilus bacteria was about 104%.
  • the bacterial count ratio of Bulgarian bacteria to Thermophilus bacteria was about 134%.
  • the bacterial count ratio of Bulgaria bacteria to Thermophilus bacteria was about 22%. From this, it was confirmed that by carrying out lactose decomposition on the medium, the growth of Bulgarian bacteria was promoted and the growth of Thermophilus was suppressed.
  • the ratio of Bulgarian bacteria to Thermophilus was about 66%.
  • the ratio of the number of Bulgarian bacteria to that of Thermophilus was about 61%.
  • the ratio of the number of Bulgarian bacteria to Thermophilus was about 129%.
  • the bacterial count ratio of Bulgaria bacteria to Thermophilus was about 13%. From this, it was confirmed that the growth of Bulgarian bacteria was promoted and the growth of Thermophilus bacteria was suppressed by producing yogurt using a lactic acid bacteria starter that had undergone lactose decomposition during the culturing process.
  • Example 4 Neutralized culture starter previously lactose-decomposed>
  • Non-fat dry milk: 250 g, lactose: 18 g, yeast extract: 4.5 g, emulsifier: 0.45 g, tap water: 1227.5 g were mixed to prepare a medium.
  • the temperature of this medium was adjusted to 40 ° C., and lactose-degrading enzyme (GODO-YNL, Godo Sakesei Co., Ltd.) was added at 0.1% by weight. After the lactose decomposition rate in the medium reached 100%, it was heated (disinfected) at 121 ° C. for 1 minute, and then cooled to 39.5 ° C.
  • lactose-degrading enzyme GODO-YNL, Godo Sakesei Co., Ltd.
  • lactic acid bacteria starter obtained here was cultured under the same conditions and procedures as described above to produce a secondary lactic acid bacteria starter.
  • raw milk 800 g
  • skim milk powder 20 g
  • sugar 45 g
  • tap water 100 g
  • the raw milk is filled into a cup container (capacity: 100 g, made of plastic), and the lactic acid acidity is increased in the fermentation chamber (43 ° C.).
  • a refrigerator 10 ° C. or lower
  • the mixture was cooled to 10 ° C. or lower to produce a primary lactic acid bacteria starter (Comparative Example 2). Furthermore, the primary lactic acid bacteria starter obtained here was cultured under the same conditions and procedures as described above to produce a secondary lactic acid bacteria starter.
  • raw milk 800 g
  • skim milk powder 20 g
  • sugar 45 g
  • tap water 100 g
  • the raw milk is filled into a cup container (capacity: 100 g, made of plastic), and the lactic acid acidity is increased in the fermentation chamber (43 ° C.).
  • a refrigerator 10 ° C. or lower
  • ⁇ Discussion> The numbers of Bulgarian bacteria and Thermophilus bacteria in Example 4 and Comparative Example 2 described above are shown in Table 2 below.
  • Table 2 also in the neutralization culture starter, by carrying out lactose decomposition on the medium in the culture process according to each example, lactic acid bacteria starter and fermented milk obtained using the same (yogurt product) Compared with the fermented milk of the comparative example, it was confirmed that the number of Bulgarian bacteria was relatively increased compared to Thermophilus.
  • the lactic acid bacteria starter obtained by the present invention has the same number of Bulgarian bacteria as Thermophilus, regardless of how many times it is passaged (planted) as compared with the comparative example. It was confirmed that the effect of the present invention that it is in an increasing tendency appears.
  • Non-fat dry milk: 80 g and tap water: 720 g were mixed to prepare a medium.
  • the temperature of the raw milk was adjusted to 5 ° C., and lactose-degrading enzyme (GODO-YNL, Godo Sakesei Co., Ltd.) was added at 0.1% by weight.
  • lactose decomposition rate in the raw milk reached 80% or higher, it was heated (sterilized) at 95 ° C for 5 minutes and then cooled to 40 ° C.
  • the lactic acid bacteria starter (Example 5) was manufactured by cooling at 10 ° C. or lower.
  • the numbers of Bulgarian bacteria and Thermophilus bacteria contained in the lactic acid bacteria starter were measured when the temperature reached 10 ° C., they were 67.0 ⁇ 10 7 cfu / g and 68.0 ⁇ 10 7 cfu / g, respectively.
  • the EPS concentration extracellular polysaccharide concentration
  • raw milk 800 g
  • skim milk powder 20 g
  • sugar 45 g
  • tap water 100 g
  • the lactic acid bacteria starter (Example 5) was inoculated at 3% by weight and then filled into a cup container (capacity: 100 g, made of plastic), and the lactic acid acidity reached 0.8% in the fermentation chamber (43 ° C.). Then, the mixture was allowed to stand for fermentation, and then cooled in a refrigerator (10 ° C. or lower) to produce a set type yogurt (fermented milk).
  • ⁇ Comparative Example 3 Lactose is not degraded>
  • Non-fat dry milk: 80 g and tap water: 720 g were mixed to prepare a medium.
  • the raw milk was heated (sterilized) at 95 ° C. for 5 minutes, cooled to 40 ° C., and inoculated with 0.15% by weight of lactic acid bacteria including Bulgarian bacteria and Thermofilus bacteria.
  • the fermentation was allowed to stand until the lactic acid acidity reached 0.75%, and then cooled in the refrigerator (10 ° C. or lower) to produce a lactic acid bacteria starter (Comparative Example 3).
  • raw milk 800 g
  • skim milk powder 20 g
  • sugar 45 g
  • tap water 100 g
  • raw milk heated (sterilized) at 95 ° C. for 5 minutes, and then cooled to 43 ° C.
  • inoculating the above lactic acid bacteria starter (Comparative Example 3) at 3% by weight, it was filled into a cup container (capacity: 100 g, made of plastic), and the lactic acid acidity reached 0.8% in the fermentation chamber (43 ° C.).
  • the mixture was allowed to stand for fermentation, and then cooled in a refrigerator (10 ° C. or lower) to produce a set type yogurt (fermented milk).
  • Table 3 collectively shows the number of Bulgarian bacteria, the number of Thermophilus bacteria, and the EPS concentration in Example 5 and Comparative Example 1 described above.
  • Table 3 the lactobacillus starter and fermented milk (yogurt product) obtained using the lactose bacteria starter and the fermented milk (yogurt product) obtained by carrying out lactose decomposition on the medium in the lactic acid bacteria starter culture process according to Example 5 Compared with fermented milk, the number of Bulgarian bacteria was relatively increased compared to Thermofilus. Further, in Example 5, it was confirmed that the EPS concentration exceeded that of Comparative Example 3 at each stage of the lactic acid bacteria starter and the set type yogurt.
  • the present invention relates to a method for producing a lactic acid bacteria starter and a method for producing fermented milk. Therefore, the present invention can be suitably used in the manufacturing industry of fermented milk such as yogurt.

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Abstract

[Problem] To promote growth of the Lactobacillus bulgaricus included in yoghurt. [Solution] A method for producing a lactobacillus starter used in order to obtain yoghurt through the fermentation of raw milk, said method comprising a culture medium preparation step for preparing a culture medium including a milk component, a culture medium sterilization step for sterilizing the culture medium, a lactobacillus inoculation step for inoculating a lactobacillus including Lactobacillus bulgaricus into the sterilized culture medium, and a culture medium fermentation step for fermenting the culture medium after inoculation of the lactobacillus, said method further comprising a lactose degradation step for degrading the lactose in the culture medium prior to the culture medium fermentation step.

Description

乳酸菌スターター及び発酵乳の製造方法Lactic acid bacteria starter and method for producing fermented milk
　本発明は，乳酸菌スターターの製造方法，及びその乳酸菌スターターを利用した発酵乳の製造方法に関する。 The present invention relates to a method for producing a lactic acid bacteria starter and a method for producing fermented milk using the lactic acid bacteria starter.
　以前から，発酵乳を製造するにあたり，乳酸菌用の培地でマザースターターを培養して中間発酵を行い，原料乳の発酵に利用する乳酸菌スターターを得ることが知られている。そして，ここで得られた乳酸菌スターターを原料乳（ヨーグルトミックス）に接種し，原料乳を所定温度と所定時間で保持して発酵させることで，発酵乳を製造することとなる。また，発酵乳の製造においては，乳酸菌スターターを何段階にも亘って培養し，初代のマザースターターから何世代にも亘って段階的に植え継ぎ，それぞれの段階で乳酸菌スターターを活性化しながらスケールアップすることもある。 It has long been known that when producing fermented milk, a mother starter is cultured in a medium for lactic acid bacteria and subjected to intermediate fermentation to obtain a lactic acid bacteria starter used for fermentation of raw milk. And fermented milk will be manufactured by inoculating raw material milk (yogurt mix) with the lactic-acid-bacteria starter obtained here, and fermenting by hold | maintaining raw material milk at predetermined temperature and predetermined time. In addition, in the production of fermented milk, lactic acid bacteria starters are cultured over several stages, and then transferred from the original mother starter over several generations, and scaled up while activating the lactic acid bacteria starters at each stage. Sometimes.
　また，以前から，原料乳にブルガリア菌とサーモフィルス菌の２種の乳酸菌をスターターとして接種して発酵させることにより，ヨーグルトを得る方法が知られている。このようなヨーグルトでは，一般的に，ブルガリア菌とサーモフィルス菌の菌数の比率が，１：４～１：５程度であり，ブルガリア菌に対して，サーモフィルス菌が圧倒的に多数で存在している。 In addition, a method for obtaining yogurt by inoculating and fermenting two types of lactic acid bacteria of Bulgarian bacteria and Thermophilus bacteria as starters in raw milk has been known. In such yogurt, the ratio of the number of Bulgarian bacteria to Thermophilus bacteria is generally about 1: 4 to 1: 5, and there are overwhelmingly large numbers of Thermofilus bacteria compared to Bulgarian bacteria. is doing.
　ところで，ヨーグルトには，ブルガリア菌の菌数に規格（例えば，１６日間の保存後で，１０６cfu/g以上）が設定されている製品がある。また，ヨーグルトには，ブルガリア菌によって産出される機能性の多糖体（ＥＰＳ：Exopolysaccharide）が所定量で含有されていることを特徴とする製品も存在する。このようなヨーグルトでは，その製造過程において，ブルガリア菌の菌数を増加させることが望まれる。 By the way, there is a product in which a standard (for example, 10 6 cfu / g or more after storage for 16 days) is set for the number of Bulgarian bacteria in yogurt. There is also a product characterized in that yogurt contains a predetermined amount of functional polysaccharide (EPS) produced by Bulgarian bacteria. In such a yogurt, it is desired to increase the number of Bulgarian bacteria in the production process.
　この点，以前から，原料乳にｐＨ緩衝剤を添加して発酵や培養させることで，乳酸菌の増殖を促進させる方法が知られている。 In this regard, a method for promoting the growth of lactic acid bacteria by adding a pH buffer to raw material milk and fermenting or culturing it has been known.
　例えば，特許文献１には，原料乳にオレイン酸などを添加する低脂肪ヨーグルトの製造方法が開示されている。特許文献１によれば，オレイン酸などを用いることで，低脂肪ヨーグルトにおける乳酸菌の生残性を向上させることができると提案されている。 For example, Patent Document 1 discloses a method for producing low-fat yogurt in which oleic acid or the like is added to raw milk. According to Patent Document 1, it is proposed that the survival of lactic acid bacteria in low-fat yogurt can be improved by using oleic acid or the like.
　また，特許文献２には，原料乳にグァバ葉エキスを添加する発酵食品の製造方法が開示されている。特許文献２によれば，グァバ葉エキスを用いることで，乳酸菌の生残性改善剤や乳酸菌の増殖促進剤として機能するため，発酵食品における乳酸菌の生残性を向上させることができると提案されている。 Patent Document 2 discloses a fermented food production method in which guava leaf extract is added to raw milk. According to Patent Document 2, it is proposed that the use of guava leaf extract can improve the survival of lactic acid bacteria in fermented foods because it functions as a survival improver for lactic acid bacteria and a growth promoter for lactic acid bacteria. ing.
　また，特許文献３には，原料乳にアラビアガムを添加する発酵食品の製造方法が開示されている。特許文献３によれば，アラビアガムを用いることで，発酵食品の保存中におけるビフィズス菌の生存率を増加させることができると提案されている。 Patent Document 3 discloses a method for producing fermented foods in which gum arabic is added to raw milk. According to Patent Document 3, it is proposed that the survival rate of bifidobacteria during storage of fermented food can be increased by using gum arabic.
特開２００１－０４５９６８号公報JP 2001-045968 A 特開２０１０－１１９３０５号公報JP 2010-119305 A 特表２０１０－５０５３９０号公報Special table 2010-505390
　しかしながら，上記した従来技術のように，乳酸菌の菌数を増加させるために，発酵乳の元となる原料乳にｐＨ緩衝剤などの乳酸菌の増殖促進剤を直接的に添加すると，この増殖促進剤が原因となって，乳本来の風味とは異なる雑味，苦味，酸味などが発生するという問題があった。このため，従来の乳酸菌の増殖促進剤を用いる場合，発酵乳の風味の調整が困難であった。 However, in order to increase the number of lactic acid bacteria as in the prior art described above, if a growth promoter for lactic acid bacteria such as a pH buffer is added directly to the raw milk that is the source of fermented milk, this growth promoter As a result, there was a problem that miscellaneous taste, bitterness, sourness, etc., different from the original flavor of milk occurred. For this reason, when using the conventional lactic acid bacteria growth promoter, it is difficult to adjust the flavor of the fermented milk.
　また，ブルガリア菌とサーモフィルス菌の両方を含む発酵乳において，従来の乳酸菌の増殖促進剤を用いる場合，ブルガリア菌とサーモフィルス菌の両方の菌数が一緒に増加することとなる。つまり，従来の乳酸菌の増殖促進剤を用いる場合，ブルガリア菌とサーモフィルス菌の増殖が一緒に促進されるため，ブルガリア菌の増殖を相対的に促進することが困難であり，その結果として，ブルガリア菌に由来する多糖体の産生を促進することが困難であった。これに対し，上述したようなヨーグルトでは，その製造過程において，ブルガリア菌の増殖のみを促進させて，サーモフィルス菌の増殖を促進させなくてもよい製品も存在する。このとき，ブルガリア菌とサーモフィルス菌の両方を含む発酵乳において，ブルガリア菌の菌数の比率を高めることで，ブルガリア菌に由来する多糖体の生産量を増やすことが可能となる。 Moreover, in the fermented milk containing both Bulgarian bacteria and Thermophilus bacteria, when the conventional lactic acid bacteria growth promoter is used, both the number of Bulgarian bacteria and Thermophilus bacteria will increase together. In other words, when a conventional lactic acid bacteria growth promoter is used, the growth of Bulgarian bacteria and Thermophilus bacteria are promoted together, and thus it is difficult to relatively promote the growth of Bulgarian bacteria. It was difficult to promote the production of polysaccharides derived from bacteria. On the other hand, in the yogurt as described above, there is a product that only promotes the growth of Bulgarian bacteria and does not need to promote the growth of Thermophilus bacteria during the production process. At this time, it is possible to increase the production amount of polysaccharides derived from Bulgaria bacteria by increasing the ratio of the number of Bulgaria bacteria in fermented milk containing both Bulgaria bacteria and Thermophilus bacteria.
　そこで，本発明は，発酵乳に含まれるブルガリア菌の増殖を促進できる技術を提供することを目的とする。特に，本発明は，ブルガリア菌とサーモフィルス菌を含む発酵乳において，ブルガリア菌の増殖を相対的に促進し，サーモフィルス菌の増殖を相対的に抑制することを目的とする。 Therefore, an object of the present invention is to provide a technique capable of promoting the growth of Bulgarian bacteria contained in fermented milk. In particular, an object of the present invention is to relatively promote the growth of Bulgaria bacteria and relatively suppress the growth of Thermophilus bacteria in fermented milk containing Bulgaria bacteria and Thermophilus bacteria.
　本発明の発明者らは，従来の問題を解決する手段について鋭意検討した結果，原料乳の発酵に利用する乳酸菌スターターを製造する際に，乳酸菌スターター用の培地に対して乳糖分解を実施することで，そのような乳酸菌スターターを利用して得た発酵乳では，ブルガリア菌が相対的に増加することを見出した。そして，本発明者らは，上記知見に基づけば，発酵乳に含まれるブルガリア菌の増殖を促進することができることに想到し，本発明を完成させた。具体的に説明すると，本発明は，以下の工程を有する。 The inventors of the present invention have conducted intensive studies on means for solving the conventional problems. As a result, when producing a lactic acid bacteria starter to be used for fermentation of raw milk, lactose decomposition is performed on the medium for the lactic acid bacteria starter. In the fermented milk obtained using such a lactic acid bacteria starter, the Bulgarian bacteria were found to increase relatively. Then, the present inventors have conceived that, based on the above findings, the growth of Bulgarian bacteria contained in fermented milk can be promoted, and the present invention has been completed. Specifically, the present invention has the following steps.
　本発明の第１の側面は，乳酸菌スターターの製造方法に関する。乳酸菌スターターは，基本的に，原料乳を発酵させて発酵乳を得るのに利用される。なお，乳酸菌スターターの「利用」には，本発明によって得られた乳酸菌スターターを原料乳に直接接種することの他に，本発明によって得られた乳酸菌スターターを培地でさらに１回以上培養して，その培養後の次世代以降の乳酸菌スターターを原料乳に接種することをも含む。 The first aspect of the present invention relates to a method for producing a lactic acid bacteria starter. The lactic acid bacteria starter is basically used to ferment raw milk to obtain fermented milk. In addition, in “use” of the lactic acid bacteria starter, in addition to directly inoculating the raw milk with the lactic acid bacteria starter obtained by the present invention, the lactic acid bacteria starter obtained by the present invention is further cultured in the medium at least once, It also includes inoculating raw milk with the lactic acid bacteria starter of the next generation after the culture.
　本発明に係る乳酸菌スターターの製造方法は，培地調製工程，培地殺菌工程，乳酸菌接種工程，培地発酵工程（培養工程），及び乳糖分解工程を含む。培地調製工程は，乳成分を含む培地を調製する工程である。培地殺菌工程は，例えば加熱により培地を殺菌する工程である。乳酸菌接種工程は，殺菌後の培地にブルガリア菌を含む乳酸菌を接種する工程である。培地発酵工程は，乳酸菌接種後の培地を発酵させる工程である。乳糖分解工程は，培地内の乳糖を分解する工程である。本発明において，乳糖分解工程は，培地発酵工程よりも前に，培地内の乳糖を分解する工程であることを特徴としている。 The method for producing a lactic acid bacteria starter according to the present invention includes a medium preparation process, a medium sterilization process, a lactic acid bacteria inoculation process, a medium fermentation process (culture process), and a lactose decomposition process. The medium preparation step is a step of preparing a medium containing milk components. The medium sterilization step is a step of sterilizing the medium by heating, for example. The lactic acid bacteria inoculation step is a step of inoculating a sterilized medium with lactic acid bacteria containing Bulgarian bacteria. The medium fermentation step is a step of fermenting the medium after inoculation with lactic acid bacteria. The lactose decomposition step is a step of decomposing lactose in the medium. In the present invention, the lactose decomposition step is a step in which lactose in the medium is decomposed before the medium fermentation step.
　本発明において，乳糖分解工程は，培地殺菌工程の前に行われてもよい。 In the present invention, the lactose decomposition step may be performed before the medium sterilization step.
　本発明において，乳糖分解工程は，培地殺菌工程後，乳酸菌接種工程の前に行われてもよい。 In the present invention, the lactose decomposition step may be performed after the medium sterilization step and before the lactic acid bacteria inoculation step.
　本発明において，乳糖分解工程は，培地に乳酸菌と同時に乳糖分解酵素を添加することによって，培地内の乳糖を分解する工程であってもよい。また，乳糖分解工程は，乳酸菌接種後の培地を発酵温度域（例えば３５℃～５０℃）に昇温する前に培地に乳糖分解酵素を添加することによって，培地内の乳糖を分解する工程であってもよい。 In the present invention, the lactose decomposition step may be a step of degrading lactose in the medium by adding lactose decomposing enzyme simultaneously with lactic acid bacteria to the medium. The lactose decomposition step is a step of degrading lactose in the medium by adding lactose-degrading enzyme to the medium before raising the temperature of the medium after inoculation with lactic acid bacteria to the fermentation temperature range (for example, 35 ° C. to 50 ° C.). There may be.
　本発明において，乳酸菌は，ブルガリア菌に加えて，サーモフィルス菌をさらに含むことが好ましい。 In the present invention, the lactic acid bacterium preferably further contains Thermophilus bacterium in addition to Bulgaria bacterium.
　本発明において，乳糖分解工程は，培地内の乳糖分解率を７０％以上とする工程であることが好ましい。具体的に説明すると，少なくとも培地が発酵温度域（例えば３５℃～５０℃）に達した時点において，培地の乳糖分解率を７０％以上となることが好ましい。また，例えば，培地殺菌工程の前に乳糖分解工程を行う場合には，培地を殺菌した時点で培地の乳糖分解率は７０％以上であることが好ましい。さらに，培地殺菌工程後乳酸菌接種工程の前に乳糖分解工程を行う場合には，培地に乳酸菌を接種した時点で培地の乳糖分解率は７０％以上であることが好ましい。 In the present invention, the lactose decomposition step is preferably a step in which the lactose decomposition rate in the medium is 70% or more. Specifically, it is preferable that the lactose decomposition rate of the medium becomes 70% or more at least when the medium reaches the fermentation temperature range (for example, 35 ° C. to 50 ° C.). For example, when the lactose decomposition step is performed before the medium sterilization step, the lactose decomposition rate of the medium is preferably 70% or more when the medium is sterilized. Furthermore, when the lactose decomposition step is performed after the medium sterilization step and before the lactic acid bacteria inoculation step, the lactose decomposition rate of the medium is preferably 70% or more when the medium is inoculated with lactic acid bacteria.
　上記のように，本発明では，乳酸菌スターターを製造する際に乳酸菌スターター用の培地に対して乳糖分解を実施し，この乳酸菌スターターを利用して発酵乳を製造することにより，発酵乳におけるブルガリア菌の菌数を増加させることができる。特に，後述する実施例に示されるとおり，ブルガリア菌とサーモフィルス菌を含む発酵乳において，本発明によって製造された乳酸菌スターターを利用することで，ブルガリア菌の増殖を相対的に促進し，サーモフィルス菌の増殖を相対的に抑制することができる。ブルガリア菌とサーモフィルス菌を含む乳酸菌スターターは，継代（菌の植え継ぎ）を重ねるにしたがってサーモフィルス菌の方が優勢になるのが技術常識であったが，本発明によれば，乳酸菌スターターよりも発酵乳のほうがブルガリア菌の比率が高くなる。このため，乳酸菌スターターの製造時に乳糖分解を実施することで，そこに含まれるブルガリア菌の活力（増殖力）が強くなっているものと推察される。このように，本発明は，発酵乳の元となる原料乳に対して乳糖分解を実施するのではなく，乳酸菌スターター用の培地に対して乳糖分解を実施することに特徴がある。ただし，本発明は，原料乳に対して乳糖分解を行うことを除くものではない。なお，従来から，発酵乳の元となる原料乳に対して乳糖分解を実施する技術は知られていた。しかし，これは，原料乳に含まれる乳糖を分解してグルコース及びガラクトースを生成することで発酵乳に甘味を付与することを目的とした技術であり，本発明とは乳糖分解を行う対象と目的が異なる。 As described above, in the present invention, when producing a lactic acid bacterium starter, lactose decomposition is performed on a medium for the lactic acid bacterium starter, and fermented milk is produced using the lactic acid bacterium starter. The number of bacteria can be increased. In particular, as shown in the examples described later, in fermented milk containing Bulgaria and thermophilus bacteria, by utilizing the lactic acid bacteria starter produced according to the present invention, the growth of Bulgaria bacteria is relatively accelerated, and thermophilus is produced. The growth of bacteria can be relatively suppressed. As for the lactic acid bacteria starter containing Bulgarian bacteria and thermophilus bacteria, it was the technical common sense that the thermophilus bacteria became more dominant as the passage (planting of the bacteria) was repeated, but according to the present invention, the lactic acid bacteria starter Fermented milk has a higher proportion of Bulgarian bacteria. For this reason, it is presumed that the activity (proliferation ability) of the Bulgarian bacteria contained therein is strengthened by carrying out lactose decomposition during the production of the lactic acid bacteria starter. As described above, the present invention is characterized in that lactose decomposition is not performed on the raw material milk that is the basis of fermented milk, but is performed on the medium for the lactic acid bacteria starter. However, the present invention does not exclude performing lactose decomposition on raw milk. Conventionally, there has been known a technique for performing lactose decomposition on raw milk that is a source of fermented milk. However, this is a technique aimed at imparting sweetness to fermented milk by decomposing lactose contained in raw milk to produce glucose and galactose, and the present invention is intended for the purpose and purpose of lactose decomposition. Is different.
　本発明の第２の側面は，発酵乳の製造方法に関する。本発明に係る発酵乳の製造方法は，上記した第１の側面に係る乳酸菌スターターの製造方法により得られた乳酸菌スターターを，発酵乳の製造に利用する。発酵乳の製造する際には，乳酸菌スターターを原料乳に直接接種することしてもよいし，乳酸菌スターターを培地でさらに１回以上培養して，その培養後の次世代以降の乳酸菌スターターを原料乳に接種することしてもよい。 The second aspect of the present invention relates to a method for producing fermented milk. The method for producing fermented milk according to the present invention utilizes the lactic acid bacteria starter obtained by the method for producing a lactic acid bacteria starter according to the first aspect described above for the production of fermented milk. When producing fermented milk, the lactic acid bacteria starter may be directly inoculated into the raw milk, or the lactic acid bacteria starter is further cultured once or more in the medium, and the lactic acid bacteria starter from the next generation onwards after the cultivation is used as the raw milk. You may inoculate.
　本発明によれば，発酵乳に含まれるブルガリア菌の増殖を促進することができる。また，本発明によれば，ブルガリア菌とサーモフィルス菌を含む発酵乳において，ブルガリア菌の増殖を相対的に促進し，サーモフィルス菌の増殖を相対的に抑制することができる。 According to the present invention, the growth of Bulgarian bacteria contained in fermented milk can be promoted. Moreover, according to this invention, in fermented milk containing a Bulgaria bacterium and a thermophilus bacterium, the proliferation of a Bulgaria bacterium can be accelerated | stimulated relatively and the proliferation of a thermophilus bacterium can be suppressed relatively.
図１は，本発明に係る乳酸菌スターターの製造方法及び発酵乳の製造方法に含まれる各工程の一例を示したフロー図である。FIG. 1 is a flowchart showing an example of each step included in the method for producing a lactic acid bacteria starter and the method for producing fermented milk according to the present invention.
　以下，図面を用いて本発明を実施するための形態について説明する。本発明は，以下に説明する形態に限定されるものではなく，以下の形態から当業者が自明な範囲で適宜変更したものも含む。
　なお，本願明細書において，「Ａ～Ｂ」とは「Ａ以上Ｂ以下」であることを意味する。 Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. This invention is not limited to the form demonstrated below, The thing suitably changed in the range obvious to those skilled in the art from the following forms is also included.
In the present specification, “A to B” means “A or more and B or less”.
　図１は，乳酸菌スターターを製造するための各工程（Ｓ１～Ｓ５）と，発酵乳を製造するための各工程（Ｓ６～Ｓ９）を示している。以下では，図１に示したフロー図に従って説明を行う。 FIG. 1 shows each step (S1 to S5) for producing a lactic acid bacteria starter and each step (S6 to S9) for producing fermented milk. Below, it demonstrates according to the flowchart shown in FIG.
　乳酸菌スターターの製造方法は，種菌となる乳酸菌を培地にて培養し，中間発酵させることで，原料乳の発酵に利用する乳酸菌スターターを製造する方法である。「乳酸菌スターター」は，ある乳酸菌を培地（溶液）で培養し，中間発酵を経て調製されたものを含む。乳酸菌スターターは，基本的に，乳酸菌とそれを培養した培地溶液とを構成要素として含むものである。また，乳酸菌スターターには，発酵乳の元となる原料乳に直接接種するものの他に，この乳酸菌スターターを別の培地に接種して，乳酸菌をさらに増殖（スケールアップ）させた次世代以降ものが含まれる。 The method for producing a lactic acid bacteria starter is a method for producing a lactic acid bacteria starter used for fermentation of raw material milk by culturing lactic acid bacteria serving as inoculums in a medium and subjecting them to intermediate fermentation. “Lactic acid bacteria starter” includes those prepared by culturing a certain lactic acid bacteria in a medium (solution) and intermediate fermentation. The lactic acid bacteria starter basically includes lactic acid bacteria and a medium solution in which the lactic acid bacteria are cultured as components. In addition to the lactic acid bacteria starter that is directly inoculated into the raw milk that is the source of fermented milk, the lactic acid bacteria starter includes the next generation and beyond, in which the lactic acid bacteria starter is further inoculated into another medium and scaled up. included.
　図１に示されるように，乳酸菌スターターの製造方法は，培地調製工程（Ｓ１），培地殺菌工程（Ｓ２），乳酸菌接種工程（Ｓ３），培養工程（培地発酵工程）（Ｓ４），及び乳糖分解工程（Ｓ５）を含む。また，乳糖分解工程（Ｓ５）は，培地調製工程と培地殺菌工程の間に行われる第１の乳糖分解工程（Ｓ５－１）と，培地殺菌工程と乳酸菌接種工程の間に行われ第２の乳糖分解工程（Ｓ５－２）と，乳酸菌接種工程と培養工程の間に行われる第３の乳糖分解工程（Ｓ５－３）とがある。第１から第３の乳糖分解工程は，少なくとも一つ以上を行えばよく，全て行うこととしてもよい。 As shown in FIG. 1, the method for producing a lactic acid bacteria starter includes a medium preparation process (S1), a medium sterilization process (S2), a lactic acid bacteria inoculation process (S3), a culture process (medium fermentation process) (S4), and lactose decomposition. Including a step (S5). The lactose decomposition step (S5) is performed between the first lactose decomposition step (S5-1) performed between the medium preparation step and the medium sterilization step, and between the medium sterilization step and the lactic acid bacteria inoculation step. There are a lactose decomposition step (S5-2) and a third lactose decomposition step (S5-3) performed between the lactic acid bacteria inoculation step and the culture step. The first to third lactose decomposition steps may be performed at least one or all of them.
　培地調製工程（Ｓ１）は，乳酸菌を接種する培地を調製する工程である。培地は，乳酸菌を培養するための溶液である。乳酸菌を培地に接種し，その培地で乳酸菌を培養することで，乳酸菌の数を増加させることができる。培地は，無脂乳固形分（ＳＮＦ）を，６重量％以上，好ましくは８重量％以上，より好ましくは９重量％以上含有する。培地の無脂乳固形分の上限は特に限定されないが，例えば３０重量％以下又は２５重量％以下であることが好ましい。特に，無脂乳固形分は，脱脂粉乳由来のものであることが好ましい。なお，脱脂粉乳は，およそ９５％が無脂乳固形分であり，残余の大部分が水分である。また，培地は，無脂乳固形分と水分のみからなるものであることが好ましい。つまり，培地は，無脂乳固形分を，６重量％以上で含み，残余が水分からなる。 The medium preparation step (S1) is a step of preparing a medium for inoculating lactic acid bacteria. The medium is a solution for culturing lactic acid bacteria. The number of lactic acid bacteria can be increased by inoculating the medium with lactic acid bacteria and culturing the lactic acid bacteria in the medium. The medium contains non-fat milk solids (SNF) of 6% by weight or more, preferably 8% by weight or more, more preferably 9% by weight or more. Although the upper limit of the non-fat milk solid content of the medium is not particularly limited, it is preferably, for example, 30% by weight or less or 25% by weight or less. In particular, the non-fat milk solid content is preferably derived from skim milk powder. In addition, about 95% of skim milk powder is nonfat milk solid content, and most of the remainder is moisture. Moreover, it is preferable that a culture medium consists only of non-fat milk solid content and a water | moisture content. In other words, the medium contains non-fat milk solids at 6% by weight or more, and the remainder consists of moisture.
　殺菌工程（Ｓ２）は，培地調製工程で調製された培地を，例えば加熱によって殺菌する工程である。殺菌工程では，培地の雑菌を殺菌できる程度に，加熱温度及び加熱時間を調整して加熱処理すればよい。本発明においては，培地を８０℃以上，９０℃以上，９５℃以上，又は１００℃以上に加熱することが好ましい。加熱殺菌には，公知の方法を用いることができる。例えば，加熱殺菌では，プレート式熱交換器，チューブ式熱交換器，スチームインジェクション式加熱装置，スチームインフュージョン式加熱装置，通電式加熱装置などによって加熱処理を行えばよく，ジャケット付のタンクによって加熱処理を行ってもよい。なお，培地の殺菌は加熱に限られず，例えば紫外線照射など公知の方法によって行うこともできる。 The sterilization step (S2) is a step of sterilizing the medium prepared in the medium preparation step, for example, by heating. In the sterilization process, the heating temperature and the heating time may be adjusted so as to sterilize the bacteria in the medium. In the present invention, the medium is preferably heated to 80 ° C. or higher, 90 ° C. or higher, 95 ° C. or higher, or 100 ° C. or higher. A known method can be used for the heat sterilization. For example, in heat sterilization, heat treatment may be performed with a plate heat exchanger, tube heat exchanger, steam injection heating device, steam infusion heating device, energizing heating device, etc., and heating is performed with a jacketed tank. Processing may be performed. The sterilization of the medium is not limited to heating, and can be performed by a known method such as ultraviolet irradiation.
　また，加熱によって培地を殺菌処理した場合，乳酸菌添加工程の前に，高温になっている培地を乳酸菌の培養に適した温度域（培養温度域）にまで冷却することが好ましい。培養温度域とは，微生物（乳酸菌など）が活性化して，当該微生物の増殖促進される温度を意味する。例えば乳酸菌の培養温度域は，３０～６０℃が一般的である。本発明においては，加熱殺菌後に高温になっている培地を，例えば３０～６０℃の培養温度域にまで冷却することが好ましく，３５～５５℃まで冷却することがより好ましい。 In addition, when the medium is sterilized by heating, it is preferable to cool the medium at a high temperature to a temperature range (culture temperature range) suitable for culturing lactic acid bacteria before the lactic acid bacteria addition step. The culture temperature range means a temperature at which microorganisms (such as lactic acid bacteria) are activated to promote the growth of the microorganisms. For example, the culture temperature range of lactic acid bacteria is generally 30 to 60 ° C. In the present invention, it is preferable to cool the medium, which has become high after heat sterilization, to a culture temperature range of 30 to 60 ° C., for example, and more preferably to 35 to 55 ° C.
　乳酸菌接種工程（Ｓ３）は，培養温度域にある培地に，乳酸菌を接種（添加）する工程である。なお，乳酸菌接種工程では，加熱殺菌後に培地が所定温度まで低下した後に乳酸菌を接種してもよいし，加熱殺菌後に培地が所定温度まで低下している最中に乳酸菌を接種してもよい。培地に接種する乳酸菌としては，凍結濃縮菌，凍結ペレット，凍結乾燥粉末などを用いることができる。乳酸菌接種工程においては，乳酸菌を，培地に対して，０．０５重量％以上で添加することが好ましい。具体的には，乳酸菌は，培地に対して，０．０５～１０重量％又は０．１～５重量％で添加すればよい。凍結濃縮菌としては，例えば特許５９６３３８９号公報に記載されたものを用いることができる。 The lactic acid bacteria inoculation step (S3) is a step of inoculating (adding) lactic acid bacteria to the medium in the culture temperature range. In the lactic acid bacteria inoculation step, lactic acid bacteria may be inoculated after the medium has been lowered to a predetermined temperature after heat sterilization, or lactic acid bacteria may be inoculated while the medium has been lowered to a predetermined temperature after heat sterilization. As the lactic acid bacteria inoculated into the medium, freeze-concentrated bacteria, frozen pellets, freeze-dried powders, and the like can be used. In the lactic acid bacteria inoculation step, lactic acid bacteria are preferably added at 0.05% by weight or more with respect to the medium. Specifically, lactic acid bacteria may be added at 0.05 to 10% by weight or 0.1 to 5% by weight with respect to the medium. As the freeze-concentrated bacteria, for example, those described in Japanese Patent No. 5963389 can be used.
　本発明において，乳酸菌は，ブルガリア菌を含む。「ブルガリア菌」とは，ラクトバチルス・ブルガリクス（L. bulgaricus）である。また，乳酸菌はブルガリア菌に加えて，サーモフィルス菌を含むことが好ましい。「サーモフィルス菌」とは，ストレプトコッカス・サーモフィルス（S.thermophilus）である。なお，本発明において，乳酸菌には，ブルガリア菌とサーモフィルス菌の他に，公知の乳酸菌が含まれていてもよい。公知の乳酸菌の例は，ガセリ菌（ラクトバチルス・ガッセリ（L. gasseri）），ラクティス菌（ラクトコッカス・ラクティス（L. lactis）），クレモリス菌（ラクトコッカス・クレモリス（L. cremoris）），ビフィズス菌（ビフィドバクテリウム（Bifidobacterium））などある。 In the present invention, lactic acid bacteria include Bulgarian bacteria. “Bulgaria” is L. bulgaricus. Moreover, it is preferable that lactic acid bacteria contain Thermophilus bacteria in addition to Bulgarian bacteria. "Thermophilus" is Streptococcus thermophilus (S. thermophilus). In the present invention, the lactic acid bacteria may include known lactic acid bacteria in addition to Bulgarian bacteria and Thermophilus bacteria. Examples of known lactic acid bacteria include gasseri (L. gasseri), lactis (L. lactis), cremiris (L. There are bacteria such as Bifidobacterium.
　培養工程（Ｓ４）は，乳酸菌を培地で培養し，乳酸菌を増殖させる工程である。乳酸菌の培養は，培地の酸度を目安にして終了させることが好ましい。乳酸菌の培養の時間の上限は，特に限定されないが，例えば，培地の発酵がすすみ，培地の酸度が所定値となった段階で培養を終了させればよい。ここで，例えば，培養の終了の酸度は，０．７％，０．７５％，又は０．８％に設定することが好ましく，０．７～１．２％の範囲に設定すればよい。なお，本発明において，培地の酸度（乳酸酸度）は，乳等省令の「乳等の成分規格の試験法」に従って測定される。具体的には，試料の１０ｇに，炭酸ガスを含まないイオン交換水を１０ｍＬで添加してから，指示薬として，フェノールフタレイン溶液を０．５ｍＬで添加する。そして，水酸化ナトリウム溶液（０．１ｍｏｌ／Ｌ）を添加しながら，微紅色が消失しないところを限度として滴定し，その水酸化ナトリウム溶液の滴定量から試料の１００ｇ当たりの乳酸の含量を求めて，酸度（乳酸酸度）とする。なお，フェノールフタレイン溶液は，フェノールフタレインの１ｇをエタノール溶液（５０％）に溶かして１００ｍＬにフィルアップして調整される。 The culturing step (S4) is a step of cultivating lactic acid bacteria in a medium and growing the lactic acid bacteria. The cultivation of lactic acid bacteria is preferably terminated with the acidity of the medium as a guide. The upper limit of the culturing time for lactic acid bacteria is not particularly limited. For example, the culture may be terminated when fermentation of the medium proceeds and the acidity of the medium reaches a predetermined value. Here, for example, the acidity at the end of the culture is preferably set to 0.7%, 0.75%, or 0.8%, and may be set to a range of 0.7 to 1.2%. In the present invention, the acidity (lactic acidity) of the medium is measured according to the “Testing Method for Component Standards of Milk” in the Ministerial Ordinance of Milk. Specifically, 10 mL of ion exchange water not containing carbon dioxide gas is added to 10 g of the sample at 10 mL, and then a phenolphthalein solution is added at 0.5 mL as an indicator. While adding sodium hydroxide solution (0.1 mol / L), titration was performed up to the point where the faint red color did not disappear, and the content of lactic acid per 100 g of the sample was determined from the titration of the sodium hydroxide solution. , Acidity (lactic acidity). The phenolphthalein solution is prepared by dissolving 1 g of phenolphthalein in an ethanol solution (50%) and filling up to 100 mL.
　また，培養工程において，培地の温度は，３５℃以上の発酵温度域に保持されていることが好ましい。特に，培地の温度は，３５～５５℃で保持されていることが好ましく，３７～５２℃で保持されていることがより好ましく，４０～５０℃で保持されていることがさらに好ましい。また，乳酸菌スターターの培養の時間は，３時間以上，５時間以上，又は７時間以上であることが好ましい。また，培養工程においては，培地を撹拌せずに静置しておくことが好ましい。ここにいう「静置」とは，培地を攪拌しないことを意味するものであり，例えば培地を収容した容器を移動するような場合であっても，培地内が撹拌されないのであれば「静置」に該当する。このように，培養工程の間は培地を静置することで乳酸菌の増殖を促進し，培養終了までの時間を短縮することができる。 In the culturing step, the temperature of the medium is preferably maintained in the fermentation temperature range of 35 ° C. or higher. In particular, the temperature of the medium is preferably maintained at 35 to 55 ° C., more preferably 37 to 52 ° C., and further preferably 40 to 50 ° C. Moreover, it is preferable that the culture | cultivation time of a lactic acid bacteria starter is 3 hours or more, 5 hours or more, or 7 hours or more. In the culturing step, it is preferable to leave the medium without stirring. “Standing” here means that the medium is not stirred. For example, even if the container containing the medium is moved, if the inside of the medium is not stirred, It corresponds to. In this way, by allowing the medium to stand during the culturing step, the growth of lactic acid bacteria can be promoted and the time until the end of the culturing can be shortened.
　また，培養を終えた培地（すなわち所定の酸度に達した培地）は，乳酸菌の増殖が抑制される温度にまで冷却する。例えば，培地は，０～２０℃，３～１５℃，又は５～１０℃に冷却することが好ましい。なお，プレート式熱交換器，チューブ式熱交換器，真空（減圧）蒸発冷却器によって冷却処理を行えばよく，ジャケット付のタンクによって冷却処理を行ってもよい。 Also, the culture medium that has been cultured (that is, the medium that has reached a predetermined acidity) is cooled to a temperature at which the growth of lactic acid bacteria is suppressed. For example, the medium is preferably cooled to 0 to 20 ° C, 3 to 15 ° C, or 5 to 10 ° C. The cooling process may be performed by a plate heat exchanger, a tube heat exchanger, or a vacuum (reduced pressure) evaporative cooler, or by a jacketed tank.
　乳糖分解工程（Ｓ５）は，培地に含まれる乳糖（ラクトース）を分解する工程である。乳糖分解工程は，培地に乳糖分解酵素（ラクターゼなど）を添加することによって，乳糖分解行うことが好ましい。乳糖分解酵素は，アミノ酸配列の相同性からグリコシルヒドロラーゼに分類される酵素であり，乳糖をガラクトースとグルコースに加水分解する。乳糖分解酵素は，たとえば細菌又は酵母由来のものがあげられる。そして，活性の至適ｐＨとして６．３～７．５かつ失活ｐＨとして６．０～４．０があげられる。また，乳糖分解酵素としては，クルイベロミセス・ラクチス（Kluyveromyces Lactis）由来のもの又はクルイベロマイセスフラギリス（Kluyveromyces Fragilis）由来のものが好ましい。クルイベロミセス・ラクチス由来の乳糖分解酵素は，クルイベロミセス・ラクチスそのもののほか，クルイベロミセス・ラクチスから派生したものが含まれる。乳糖分解酵素は，市販されており，市販されている乳糖分解酵素の例は，ＧＯＤＯ－ＹＮＬ（合同酒精社製），ラクターゼＦ（天野エンザイム社製），ラクトレスＬ－３（大和化成社製），及びラクトレスＬ－１０（大和化成社製）である。 The lactose decomposition step (S5) is a step of decomposing lactose (lactose) contained in the medium. The lactose decomposition step is preferably performed by adding lactose-degrading enzyme (such as lactase) to the medium. Lactose-degrading enzymes are enzymes classified as glycosyl hydrolases based on amino acid sequence homology, and hydrolyze lactose into galactose and glucose. Examples of lactose-degrading enzymes include those derived from bacteria or yeast. The optimum pH for activity is 6.3 to 7.5, and the deactivation pH is 6.0 to 4.0. Moreover, as a lactose decomposing enzyme, the thing derived from Kluyveromyces actLactis or the thing derived from Kluyveromyces fragilis (Kluyveromyces Fragilis) is preferable. Lactose degrading enzymes derived from Kluyveromyces lactis include those derived from Kluyveromyces lactis as well as Kluyveromyces lactis itself. Lactose-degrading enzymes are commercially available, and examples of commercially available lactose-degrading enzymes include GODO-YNL (manufactured by Godo Shusei Co., Ltd.), lactase F (manufactured by Amano Enzyme), and lactres L-3 (manufactured by Daiwa Kasei Co., Ltd.) And Lactores L-10 (manufactured by Daiwa Kasei Co., Ltd.).
　図１に示されるように，乳糖分解工程には，培地調製工程と培地殺菌工程の間に行われる第１の乳糖分解工程（Ｓ５－１）と，培地殺菌工程と乳酸菌接種工程の間に行われ第２の乳糖分解工程（Ｓ５－２）と，乳酸菌接種工程と培養工程の間に行われる第３の乳糖分解工程（Ｓ５－３）とがある。第１から第３の乳糖分解工程は，少なくとも一つ以上を行えばよく，全て行うこととしてもよい。 As shown in FIG. 1, the lactose decomposition step is performed between the first lactose decomposition step (S5-1) performed between the medium preparation step and the medium sterilization step, and between the medium sterilization step and the lactic acid bacteria inoculation step. There is a second lactose decomposition step (S5-2) and a third lactose decomposition step (S5-3) performed between the lactic acid bacteria inoculation step and the culture step. The first to third lactose decomposition steps may be performed at least one or all of them.
　第１の乳糖分解工程（Ｓ５－１）は，培地の調製後，当該培地を加熱殺菌する前に，当該培地の乳糖分解を実施する。この場合，加熱殺菌開始時点における培地の乳糖分解率は，７０％以上であることが好ましく，８０％以上であることがより好ましく，９０％以上であることが特に好ましい。 In the first lactose decomposition step (S5-1), after the medium is prepared, the medium is subjected to lactose decomposition before heat sterilization. In this case, the lactose decomposition rate of the medium at the start of heat sterilization is preferably 70% or more, more preferably 80% or more, and particularly preferably 90% or more.
　第２の乳糖分解工程（Ｓ５－２）は，培地の加熱殺菌後，当該培地に乳酸菌を接種する前に，当該培地の乳糖分解を実施する。この場合，乳酸菌の接種時点における培地の乳糖分解率は，７０％以上であることが好ましく，８０％以上であることがより好ましく，９０％以上であることが特に好ましい。 In the second lactose decomposition step (S5-2), after the medium is heat-sterilized, the medium is subjected to lactose decomposition before the medium is inoculated with lactic acid bacteria. In this case, the lactose decomposition rate of the medium at the time of inoculation with lactic acid bacteria is preferably 70% or more, more preferably 80% or more, and particularly preferably 90% or more.
　第３の乳糖分解工程（Ｓ５－３）は，培地に乳酸菌と同時に乳糖分解酵素を添加するか，或いは乳酸菌接種後の培地を発酵温度域に昇温する前に，当該培地の乳糖分解を実施する。例えば，乳酸菌は，培地を加温し始める前に培地に接種してもよいし，培地を加温しながら培地に接種してもよい。また，乳糖分解は，培地を加温し始める前に完了させてしまってもよいし，培地を加温しながら進めてもよい。培地が発酵温度域（具体的には３５℃）に達した時点における培地の乳糖分解率は，７０％以上であることが好ましく，８０％以上であることがより好ましく，９０％以上であることが特に好ましい。なお，培地が発酵温度域に達した時点は，サーモフィルス菌が増殖を開始する時点とほぼ等しい。また，サーモフィルス菌が増殖を開始する時点は，対数増殖期に入った時点と言い換えることもできる。 In the third lactose decomposition step (S5-3), lactose decomposition enzyme is added to the medium at the same time as lactic acid bacteria, or lactose decomposition of the medium is performed before the temperature of the medium after inoculation with lactic acid bacteria is raised to the fermentation temperature range. To do. For example, the lactic acid bacteria may be inoculated into the medium before the medium starts to be heated, or may be inoculated into the medium while the medium is being heated. The lactose decomposition may be completed before the medium starts to be heated, or may be advanced while the medium is being heated. When the medium reaches the fermentation temperature range (specifically 35 ° C.), the lactose decomposition rate of the medium is preferably 70% or more, more preferably 80% or more, and 90% or more. Is particularly preferred. The time when the medium reaches the fermentation temperature range is almost equal to the time when the thermophilus starts to grow. In addition, the point in time when Thermophilus begins to grow can be rephrased as the point in the logarithmic growth phase.
　なお，本願明細書において，「乳糖分解率」は，培地溶液の固形分当りの乳糖含量を測定し，乳糖分解処理済みの培地溶液中のグルコース濃度から固形分当りのグルコース含量を測定し，以下の式により求める。
［式］乳糖分解率（％）＝［（グルコース含量）×２／乳糖含量］×１００
　「乳糖含量」は，高速液体クロマトグラフィーによるアルギニン蛍光法（ＢＵＮＳＥＫＩ　ＫＡＧＡＫＵ，第３２巻，第Ｅ２０７頁，１９８３年）により測定できる。また，「乳糖分解処理済みの培地溶液中のグルコース濃度」は，短時間でグルコース濃度を測定できるキット（例えばＴＥＲＵＭＯ株式会社のメディセーフミニ等）を使用した測定方法等により測定することができる。 In the present specification, the “lactose degradation rate” means the lactose content per solid content of the medium solution, and the glucose content per solid content is measured from the glucose concentration in the lactose-treated medium solution. It is calculated by the formula
[Formula] Lactose decomposition rate (%) = [(glucose content) × 2 / lactose content] × 100
The “lactose content” can be measured by the arginine fluorescence method (BUNSEKI KAGAKA, 32, E207, 1983) by high performance liquid chromatography. The “glucose concentration in the lactose-decomposed medium solution” can be measured by a measuring method using a kit that can measure the glucose concentration in a short period of time (for example, Medisafe Mini, etc. of TERUMO Co., Ltd.).
　上記第１から第３の乳糖分解工程のうち，乳酸菌スターターの製造効率を考えると，第１の乳糖分解工程（Ｓ５－１）又は第２の乳糖分解工程（Ｓ５－２）を行うことが特に好ましい。つまり，第３の乳糖分解工程（Ｓ５－２）の場合，乳酸菌を接種してから増殖を始めるまでの「誘導期」という短い間に乳糖分解を終わらせる必要があるため，大量の乳糖分解酵素が必要となる。これに対して，第１及び第２の乳糖分解工程では，乳糖分解を終わらせた後に乳酸菌を接種することとなり，乳糖分解の時間が特に制限されないため，少量の乳糖分解酵素で十分で所望の乳糖分解率を達成することができる。例えば，第１及び第２の乳糖分解工程の場合，培地に添加する乳糖分解酵素の量は，第３の乳糖分解工程と比較して，１０％～２０％程度で済む。このように，第１及び第２の乳糖分解工程であれば，少量の乳糖分解酵素でより確実に所望の乳糖分解率を達成することが可能である。 Of the first to third lactose decomposition steps, considering the production efficiency of the lactic acid bacteria starter, it is particularly preferable to perform the first lactose decomposition step (S5-1) or the second lactose decomposition step (S5-2). preferable. In other words, in the case of the third lactose decomposition step (S5-2), it is necessary to finish the lactose decomposition in a short period of “induction period” from the inoculation of lactic acid bacteria to the start of growth. Is required. In contrast, in the first and second lactose decomposition steps, lactose is inoculated after lactose decomposition is completed, and the time for lactose decomposition is not particularly limited. Lactose degradation rate can be achieved. For example, in the case of the first and second lactose decomposition steps, the amount of lactose-degrading enzyme added to the medium is about 10% to 20% as compared with the third lactose decomposition step. Thus, if it is the 1st and 2nd lactose decomposition process, it is possible to achieve a desired lactose decomposition rate more reliably with a small amount of lactose decomposing enzyme.
　上記の各工程（Ｓ１～Ｓ５）により，乳酸菌スターターを製造することができる。乳酸菌スターターは，後述する発酵乳の製造に利用することができる。なお，乳酸菌スターターは，乳酸菌及びそれを培養した培地成分を構成要素として含む。 A lactic acid bacteria starter can be produced by the above steps (S1 to S5). The lactic acid bacteria starter can be used for the production of fermented milk described later. The lactic acid bacteria starter includes lactic acid bacteria and a medium component in which the lactic acid bacteria are cultured as constituent elements.
　上記乳糖分解工程を含む方法により製造された乳酸菌スターターは，ブルガリア菌の増殖が相対的に促進され，サーモフィルス菌の増殖が相対的に抑制される。例えば，最終的に得られた乳酸菌スターターに含まれるブルガリア菌とサーモフィルス菌の菌数を測定したときに，ブルガリア菌の菌数は，サーモフィルス菌の菌数（１００％）に対して，６０％以上，６５％以上，又は７０％以上であることが好ましく，１００％以上であることがより好ましく，１１０％以上，又は１２０％以上であることが特に好ましい。乳糖分解工程を含まない一般的な培養方法によると，乳酸菌スターターにはサーモフィルス菌が圧倒的に多数で存在しており，ブルガリア菌の菌数は，サーモフィルス菌の菌数に対して多くても３０％程度となる。これに対して，本発明によれば，サーモフィルス菌に対するブルガリア菌の菌数の菌数を６０％以上とすることが可能である。このため，本発明によれば，ブルガリア菌の増殖を相対的に促進し，サーモフィルス菌の増殖を相対的に抑制することができる。なお，最終的に乳酸菌スターターに含まれる乳酸菌（ブルガリア菌とサーモフィルス菌）の菌数は，培養工程において所定の酸度に達した培地を冷却し，培地の温度が１０℃に到達した時点で測定する。 The lactic acid bacteria starter manufactured by the method including the lactose decomposition step relatively promotes the growth of Bulgaria bacteria and relatively suppresses the growth of Thermophilus bacteria. For example, when the number of Bulgarian bacteria and Thermophilus bacteria contained in the finally obtained lactic acid bacteria starter was measured, the number of Bulgarian bacteria was 60% of the number of Thermofilus bacteria (100%). % Or more, 65% or more, or 70% or more, more preferably 100% or more, and particularly preferably 110% or more, or 120% or more. According to a general culture method that does not include a lactose decomposition process, the lactic acid bacteria starter contains an overwhelming number of thermophilus bacteria, and the number of Bulgarian bacteria is larger than the number of thermophilus bacteria. Is about 30%. On the other hand, according to the present invention, the number of Bulgarian bacteria relative to Thermophilus can be set to 60% or more. For this reason, according to the present invention, it is possible to relatively promote the growth of Bulgarian bacteria and relatively suppress the growth of Thermophilus bacteria. In addition, the number of lactic acid bacteria (Bulgaria and Thermophilus) contained in the lactic acid bacteria starter is finally measured when the medium that has reached a predetermined acidity is cooled and the temperature of the medium reaches 10 ° C. To do.
　また，培地に接種する乳酸菌に含まれるサーモフィルス菌の菌数に対するブルガリア菌の菌数の比率（ブルガリア菌の菌数／サーモフィルス菌の菌数）の数値をαとする。また，最終的に得られた乳酸菌スターターに含まれるサーモフィルス菌の菌数に対するブルガリア菌の菌数の比率（ブルガリア菌の菌数／サーモフィルス菌の菌数）の数値をβとする。この場合において，β／αの数値は，１．１以上であることが好ましい。また，β／αの数値は，１．２以上，１．５以上，２．０以上，２．５以上，又は３．０以上となることがより好ましい。なお，β／αの数値の上限値は，特に限定されないが，例えば，２０．０とすればよい。このように，本発明によれば，サーモフィルス菌の菌数に対するブルガリア菌の菌数の比率を飛躍的に向上させることができる。すなわち，本発明によれば，ブルガリア菌の増殖を相対的に促進し，サーモフィルス菌の増殖を相対的に抑制することが可能となる。 Also, let α be the numerical value of the ratio of the number of Bulgarian bacteria to the number of Thermophilus bacteria contained in the lactic acid bacteria inoculated into the medium (the number of Bulgarian bacteria / the number of Thermofilus bacteria). Further, β is the ratio of the number of Bulgarian bacteria to the number of Thermophilus bacteria contained in the finally obtained lactic acid bacteria starter (the number of Bulgarian bacteria / the number of Thermophilus bacteria). In this case, the numerical value of β / α is preferably 1.1 or more. Further, it is more preferable that the numerical value of β / α is 1.2 or more, 1.5 or more, 2.0 or more, 2.5 or more, or 3.0 or more. Note that the upper limit of the numerical value of β / α is not particularly limited, but may be 20.0, for example. Thus, according to the present invention, the ratio of the number of Bulgarian bacteria to the number of Thermophilus bacteria can be dramatically improved. That is, according to the present invention, it is possible to relatively promote the growth of Bulgarian bacteria and relatively suppress the growth of Thermophilus bacteria.
　続いて，発酵乳の製造方法について説明する。本発明によって製造される発酵乳の例は，ヨーグルトである。ヨーグルトは，プレーンタイプやハードタイプやソフトタイプであってもよいし，ドリンクタイプであってもよい。また，発酵乳の例として，フローズンヨーグルトや，チーズの材料を挙げることができる。本発明において，発酵乳とは，日本の乳等省令で定義される「発酵乳」，「乳製品乳酸菌飲料」，「乳酸菌飲料」などのいずれであってもよい。 Subsequently, a method for producing fermented milk will be described. An example of fermented milk produced according to the present invention is yogurt. The yogurt may be a plain type, a hard type, a soft type, or a drink type. In addition, examples of fermented milk include frozen yogurt and cheese materials. In the present invention, the fermented milk may be any of “fermented milk”, “dairy lactic acid bacteria beverage”, “lactic acid bacteria beverage” and the like defined by a Japanese ordinance of milk.
　発酵乳の製造方法は，各工程（Ｓ１～Ｓ５）を経て得られた乳酸菌スターターを利用して原料乳を発酵させることにより，発酵乳を製造する方法である。図１に示されるように，発酵乳の製造方法は，原料乳調製工程（Ｓ６），原料乳殺菌工程（Ｓ７），乳酸菌スターター接種工程（Ｓ８），及び発酵工程（Ｓ９）を含む。 The method for producing fermented milk is a method for producing fermented milk by fermenting raw material milk using the lactic acid bacteria starter obtained through each step (S1 to S5). As shown in FIG. 1, the method for producing fermented milk includes a raw material milk preparation step (S6), a raw material milk sterilization step (S7), a lactic acid bacteria starter inoculation step (S8), and a fermentation step (S9).
　原料乳調製工程（Ｓ６）は，発酵乳の元となる原料乳を調製する工程である。原料乳は，ヨーグルトベースやヨーグルトミックスとも呼ばれる。本発明において，原料乳には公知のものを用いることができる。例えば，原料乳は，生乳のみからなるもの（生乳が１００％のもの）であってもよい。また，原料乳は，生乳に，脱脂粉乳，クリーム，水などを混合して調製したものであってもよい。また，原料乳は，これらの他に，殺菌乳，全脂乳，脱脂乳，全脂濃縮乳，脱脂濃縮乳，全脂粉乳，バターミルク，有塩バター，無塩バター，ホエー，ホエー粉，ホエータンパク質濃縮物（ＷＰＣ），ホエータンパク質単離物（ＷＰＩ），α－Ｌａ（アルファ－ラクトアルブミン），β－Ｌｇ（ベータ－ラクトグロブリン），乳糖などを混合（添加）して調製したものであってもよい。また，原料乳は，予め温めたゼラチン，寒天，増粘剤，ゲル化剤，安定剤，乳化剤，ショ糖，甘味料，香料，ビタミン，ミネラルなどを適宜添加して調製したものであってもよい。そして，原料乳の調製工程では，原料乳を均質化することで，原料乳に含まれる脂肪球などを微粒化（粉砕）することが好ましい。つまり，原料乳を均質化することで，発酵乳の製造過程や製造後において，原料乳や発酵乳の脂肪分が分離することや浮上することを抑制できる。 The raw material milk preparation step (S6) is a step of preparing raw material milk that is a source of fermented milk. Raw milk is also called yogurt base or yogurt mix. In the present invention, known milk can be used as raw material milk. For example, raw material milk may consist of raw milk only (raw milk is 100%). The raw milk may be prepared by mixing raw milk with skim milk powder, cream, water, and the like. In addition to these, raw milk is sterilized milk, whole milk, skim milk, whole fat concentrated milk, whole fat concentrated milk, whole fat milk powder, butter milk, salted butter, unsalted butter, whey, whey powder, Whey protein concentrate (WPC), whey protein isolate (WPI), α-La (alpha-lactalbumin), β-Lg (beta-lactoglobulin), prepared by mixing (adding) lactose, etc. There may be. In addition, raw milk may be prepared by appropriately adding pre-warmed gelatin, agar, thickener, gelling agent, stabilizer, emulsifier, sucrose, sweetener, flavor, vitamin, mineral, etc. Good. And in the raw material milk preparation process, it is preferable to atomize (pulverize) fat globules and the like contained in the raw material milk by homogenizing the raw material milk. That is, by homogenizing the raw material milk, the fat content of the raw material milk and the fermented milk can be prevented from separating and rising during the manufacturing process and after the manufacturing of the fermented milk.
　原料乳殺菌工程（Ｓ７）は，原料乳調製工程で調製された原料乳を，例えば加熱により殺菌する工程である。例えば，殺菌工程では，原料乳の雑菌を殺菌できる程度に，加熱温度及び加熱時間を調整して加熱処理すればよい。例えば，原料乳を８０℃以上，好ましくは９０℃以上に加熱することが好ましい。加熱処理には，公知の方法を用いることができる。そして，殺菌工程では，ヨーグルトがプレーンタイプやハードタイプやソフトタイプの場合などにおいて，高温短時間殺菌処理（ＨＴＳＴ）などの加熱処理を行えばよく，ヨーグルトがドリンクタイプの場合などにおいて，超高温殺菌処理（ＵＨＴ）などの加熱処理を行ってもよい。さらに，例えば，加熱殺菌工程では，高温短時間殺菌処理（ＨＴＳＴ）は，原料乳を８０℃～１００℃に，３分～１５分間程度で加熱する処理であればよく，超高温殺菌処理（ＵＨＴ）は，１１０℃～１５０℃に，１秒～３０秒間程度で加熱する処理であればよい。 The raw material milk sterilization step (S7) is a step of sterilizing the raw material milk prepared in the raw material milk preparation step, for example, by heating. For example, in the sterilization process, the heating temperature and the heating time may be adjusted so as to sterilize the germs of the raw material milk. For example, the raw milk is preferably heated to 80 ° C. or higher, preferably 90 ° C. or higher. A known method can be used for the heat treatment. In the sterilization process, when the yogurt is plain type, hard type or soft type, heat treatment such as high temperature short time sterilization treatment (HTST) may be performed. When yogurt is drink type, ultra high temperature sterilization is performed. Heat treatment such as treatment (UHT) may be performed. Further, for example, in the heat sterilization process, the high temperature short time sterilization process (HTST) may be a process in which the raw milk is heated to 80 ° C. to 100 ° C. for about 3 minutes to 15 minutes. ) May be a process of heating to 110 ° C. to 150 ° C. for about 1 to 30 seconds.
　また，加熱殺菌後，高温になっている原料乳を，発酵に適した温度域（発酵温度域）にまで冷却する。例えば，発酵温度域は，３０～６０℃が一般的である。本発明においては，加熱殺菌後に高温になっている原料乳を，例えば３５～５５℃の発酵温度域にまで冷却することが好ましく，４０～５０℃まで冷却することがより好ましい。 Also, after heat sterilization, the raw material milk that has become hot is cooled to a temperature range suitable for fermentation (fermentation temperature range). For example, the fermentation temperature range is generally 30 to 60 ° C. In the present invention, the raw material milk that has been heated to high temperature after heat sterilization is preferably cooled to a fermentation temperature range of 35 to 55 ° C., for example, and more preferably 40 to 50 ° C.
　乳酸菌スターター接種工程（Ｓ８）は，発酵温度域にまで冷却された培地に，前述した乳酸菌スターターの製造方法（Ｓ１～Ｓ５）を経て得られた乳酸菌スターターを接種（添加）する工程である。なお，乳酸菌スターター接種工程では，加熱殺菌後に原料乳が所定温度まで低下した後に乳酸菌スターターを接種してもよいし，加熱殺菌工程後に原料乳が所定温度まで低下している最中に乳酸菌スターターを接種してもよい。乳酸菌スターターは，原料乳に対して，０．１重量％以上で添加することが好ましい。具体的には，乳酸菌スターターは，原料乳に対して，０．１～１５重量％，０．５～１０重量％，又は１～５重量％で添加すればよい。 The lactic acid bacteria starter inoculation step (S8) is a step of inoculating (adding) the lactic acid bacteria starter obtained through the above-described lactic acid bacteria starter production method (S1 to S5) to the medium cooled to the fermentation temperature range. In the lactic acid bacteria starter inoculation step, the lactic acid bacteria starter may be inoculated after the raw milk has been lowered to a predetermined temperature after heat sterilization, or the lactic acid bacteria starter is added while the raw milk has been lowered to the predetermined temperature after the heat sterilization step. You may inoculate. The lactic acid bacteria starter is preferably added at 0.1% by weight or more with respect to the raw milk. Specifically, the lactic acid bacteria starter may be added at 0.1 to 15% by weight, 0.5 to 10% by weight, or 1 to 5% by weight with respect to the raw material milk.
　発酵工程（Ｓ９）は，乳酸菌スターターによって原料乳を発酵させる工程である。発酵工程では，乳酸菌スターターが接種された原料乳を発酵温度域（例えば３０～６０℃）に保持しながら発酵させて発酵乳を得る。本発明において，発酵工程には，公知の方法を用いることができる。例えば，発酵工程では，発酵室などによって発酵処理を行えばよく，ジャケット付のタンクによって発酵処理を行ってもよい。また，発酵工程では，ヨーグルトがプレーンタイプやハードタイプの場合などにおいて，後発酵処理を行えばよく，ヨーグルトがソフトタイプやドリンクタイプの場合などにおいて，前発酵処理を行ってもよい。さらに，例えば，発酵工程は，発酵室内の温度（発酵温度）を３０℃～６０℃程度に維持して，その発酵室内で原料乳を発酵する処理であってもよいし，ジャケット付のタンク内の温度（発酵温度）を３０～６０℃に維持し，そのタンク内で原料乳を発酵する処理であってもよい。ここで，発酵工程では，原料乳を発酵させる条件を，原料乳や乳酸菌の種類や数量，発酵乳の風味や食感などを考慮して，発酵温度や発酵時間などを適宜調整すればよい。具体的に，発酵工程では，原料乳が発酵温度域に，１時間以上で保持されていることが好ましい。そして，発酵工程では，原料乳を保持する期間（発酵時間）は，１時間～１２時間であることが好ましく，２時間～８時間であることがより好ましく，３時間～５時間であることがさらに好ましい。 The fermentation step (S9) is a step of fermenting raw material milk with a lactic acid bacteria starter. In the fermentation process, the raw milk inoculated with the lactic acid bacteria starter is fermented while being kept in a fermentation temperature range (for example, 30 to 60 ° C.) to obtain fermented milk. In the present invention, a known method can be used for the fermentation step. For example, in the fermentation process, the fermentation process may be performed in a fermentation chamber or the like, and the fermentation process may be performed in a tank with a jacket. Further, in the fermentation process, the post-fermentation process may be performed when the yogurt is a plain type or a hard type, and the pre-fermentation process may be performed when the yogurt is a soft type or a drink type. Furthermore, for example, the fermentation process may be a process in which the temperature in the fermentation chamber (fermentation temperature) is maintained at about 30 ° C. to 60 ° C. and the raw material milk is fermented in the fermentation chamber, or in a jacketed tank The temperature (fermentation temperature) may be maintained at 30 to 60 ° C., and the raw milk may be fermented in the tank. Here, in the fermentation process, the conditions for fermenting the raw milk may be adjusted as appropriate, such as the fermentation temperature and the fermentation time, in consideration of the type and quantity of the raw milk and lactic acid bacteria, the flavor and texture of the fermented milk. Specifically, in the fermentation process, it is preferable that the raw milk is maintained in the fermentation temperature range for 1 hour or more. In the fermentation process, the period for holding the raw milk (fermentation time) is preferably 1 hour to 12 hours, more preferably 2 hours to 8 hours, and more preferably 3 hours to 5 hours. Further preferred.
　発酵工程では，原料乳を発酵させる条件を，原料乳や乳酸菌の種類や数量，発酵乳の風味や食感などを考慮して，乳酸酸度（酸度）やｐＨなどを適宜調節してもよい。なお，具体的に，発酵工程では，発酵乳の乳酸酸度が０．７％以上まで到達していることが好ましく，発酵乳の乳酸酸度が０．８％以上まで到達していることが特に好ましい。なお，原料乳の酸度（乳酸酸度）は，前述した培地の酸度と同様に，乳等省令の「乳等の成分規格の試験法」に従って測定することができる。 In the fermentation process, the conditions for fermenting raw milk may be adjusted as appropriate by considering the type and quantity of raw milk and lactic acid bacteria, the flavor and texture of fermented milk, and the like. Specifically, in the fermentation process, it is preferable that the lactic acidity of the fermented milk reaches 0.7% or more, and it is particularly preferable that the lactic acidity of the fermented milk reaches 0.8% or more. . The acidity of the raw milk (lactic acidity) can be measured according to the “Testing Method for Component Standards of Milk” in the Ministerial Ordinance of Milk, similar to the acidity of the medium described above.
　発酵工程は，後発酵処理と前発酵処理のどちらであってもよい。そして，後発酵処理を行うときには，実際に製品として販売するための容器に乳酸菌スターター入りの原料乳を充填した後に，この原料乳を発酵させる。例えば，後発酵処理を行うときには，乳酸菌スターター入りの原料乳が充填された（密閉）容器を発酵室内に静置するなどして発酵させ，その得られた中間生成物である発酵乳（発酵乳カード）を，後述する再冷却工程にて冷却し，最終生成物である発酵乳（セットタイプヨーグルト，プレーンタイプヨーグルト）を得ればよい。また，前発酵処理を行うときには，実際に製品として販売するための容器に原料乳を充填する前に，原料乳を発酵させる。例えば，前発酵を行うときには，原料乳が充填されたジャケット付のタンクを静置するなどして発酵させ，その得られた中間生成物である発酵乳（発酵乳カード）を破砕や微粒化してから，後述する再冷却工程にて冷却し，必要に応じて，果肉，野菜，果汁，野菜汁，ジャム，ソース，プレパレーションなどを混合した後に，（密閉）容器に充填して，最終生成物である発酵乳（ソフトタイプヨーグルト，ドリンクタイプヨーグルト）を得ればよい。 The fermentation process may be either post-fermentation treatment or pre-fermentation treatment. And when performing a post-fermentation process, after filling the raw material milk containing a lactic acid bacteria starter into the container for actually selling as a product, this raw material milk is fermented. For example, when post-fermentation treatment is performed, fermented milk (fermented milk) that is an intermediate product obtained by fermenting (sealed) a container filled with raw milk containing lactic acid bacteria starter in a fermentation chamber. Card) is cooled in a re-cooling step to be described later, and fermented milk (set type yogurt, plain type yogurt) as a final product may be obtained. Moreover, when performing a pre-fermentation process, raw material milk is fermented before filling raw material milk into the container for actually selling as a product. For example, when pre-fermentation is carried out, the fermented milk (fermented milk card), which is the intermediate product, is fermented by leaving a jacketed tank filled with raw material milk, etc. Then, after cooling in the re-cooling process described later, and after mixing the pulp, vegetables, fruit juice, vegetable juice, jam, sauce, preparation, etc., it is filled into a (sealed) container and the final product What is necessary is just to obtain fermented milk (soft type yogurt, drink type yogurt).
　また，発酵乳の酸度が０．８％となった時点において，発酵乳における菌体外多糖の産生量（ＥＰＳ量）は，３．０mg/100g以上，３．５mg/100g以上，４．０mg/100g以上，４．５mg/100g以上，又は５．０mg/100g以上であることが好ましい。ここで，ＥＰＳ量の上限は，特に限定されないが，例えば１０．０mg/100gである。つまり，本発明によれば，発酵乳におけるＥＰＳ量も効率的に増加させることができる。 Moreover, when the acidity of fermented milk becomes 0.8%, the production amount of extracellular polysaccharide (EPS amount) in fermented milk is 3.0 mg / 100 g or more, 3.5 mg / 100 g or more, 4.0 mg. / 100 g or more, 4.5 mg / 100 g or more, or 5.0 mg / 100 g or more is preferable. Here, the upper limit of the EPS amount is not particularly limited, but is 10.0 mg / 100 g, for example. That is, according to the present invention, the amount of EPS in fermented milk can also be increased efficiently.
　発酵を終えた後（すなわち所定の酸度に達した後），発酵乳は冷却される。発酵乳を冷却することで，発酵の進行が抑制される。このとき，発酵乳を発酵温度域（例えば３０～６０℃）よりも低温になるまで冷却する。例えば発酵乳は１５℃以下まで冷却されることが好ましい。具体的には，発酵乳は，１～１５℃に冷却されていることが好ましく，３～１２℃に冷却されていることがより好ましく，５～１０℃に冷却されていることがさらに好ましい。このように，発酵乳を食用に適した温度に冷却することで，発酵乳の風味（酸味など）や食感（舌触りなど）や物性（硬さなど）が変化することを抑制や防止できる。 After the fermentation is completed (that is, after the predetermined acidity is reached), the fermented milk is cooled. The progress of fermentation is suppressed by cooling fermented milk. At this time, the fermented milk is cooled to a temperature lower than the fermentation temperature range (for example, 30 to 60 ° C.). For example, the fermented milk is preferably cooled to 15 ° C. or lower. Specifically, the fermented milk is preferably cooled to 1 to 15 ° C, more preferably 3 to 12 ° C, and even more preferably 5 to 10 ° C. As described above, by cooling the fermented milk to a temperature suitable for edible use, it is possible to suppress or prevent changes in flavor (such as acidity), texture (such as touch of the tongue), and physical properties (such as hardness) of the fermented milk.
　上記した乳糖分解工程を含む方法により製造された乳酸菌スターターを利用して発酵乳を製造することで，発酵乳に含まれるブルガリア菌の菌数を相対的に増加させることができる。例えば，最終的に得られた発酵乳に含まれるブルガリア菌とサーモフィルス菌の菌数を測定したときに，ブルガリア菌の菌数は，サーモフィルス菌の菌数（１００％）に対して，６０％以上，６５％以上，又は７０％以上であることが好ましく，１００％以上であることがより好ましく，１１０％以上，又は１２０％以上であることが特に好ましい。乳糖分解されていない一般的な乳酸菌スターターを利用して発酵乳を製造すると，その発酵乳にはサーモフィルス菌が圧倒的に多数で存在しており，ブルガリア菌の菌数は，サーモフィルス菌の菌数に対して多くても２０％程度となる。これに対して，本発明によれば，最終的な発酵乳において，サーモフィルス菌に対するブルガリア菌の菌数の菌数を６０％以上とすることが可能である。このため，本発明によれば，ブルガリア菌の増殖を相対的に促進し，サーモフィルス菌の増殖を相対的に抑制することができる。なお，最終的に発酵乳に含まれる乳酸菌（ブルガリア菌とサーモフィルス菌）の菌数は，発酵工程において所定の酸度に達した発酵乳を冷却し，発酵乳の温度が１０℃に到達した時点で測定する。 By producing fermented milk using the lactic acid bacteria starter produced by the method including the lactose decomposition step described above, the number of Bulgarian bacteria contained in the fermented milk can be relatively increased. For example, when the number of Bulgarian bacteria and Thermophilus bacteria contained in the finally obtained fermented milk was measured, the number of Bulgarian bacteria was 60% of the number of Thermophilus bacteria (100%). % Or more, 65% or more, or 70% or more, more preferably 100% or more, and particularly preferably 110% or more, or 120% or more. When fermented milk is produced using a general lactic acid bacteria starter that is not lactose-degraded, the fermented milk contains an overwhelming number of thermophilus bacteria. The number of Bulgarian bacteria is the same as that of thermophilus bacteria. It is about 20% at most with respect to the number of bacteria. On the other hand, according to the present invention, in the final fermented milk, the number of Bulgarian bacteria relative to Thermophilus bacteria can be 60% or more. For this reason, according to the present invention, it is possible to relatively promote the growth of Bulgarian bacteria and relatively suppress the growth of Thermophilus bacteria. The number of lactic acid bacteria (Bulgaria bacteria and Thermophilus bacteria) finally contained in fermented milk is determined by cooling fermented milk that has reached a predetermined acidity in the fermentation process, and when the temperature of fermented milk reaches 10 ° C. Measure with
　また，本発明によれば，乳酸菌スターターの製造方法を工夫するだけで，発酵乳に含まれるブルガリア菌の菌数を増加させることができる。そして，ブルガリア菌には，機能性の多糖体を生産するものがある。従って，本発明により得られた乳酸菌スターターを利用すれば，乳酸菌の増殖促進剤などの添加物を用いることなく，多糖体を多く含む雑味のない発酵乳を製造することができる。なお，本発明は，乳酸菌の増殖促進剤などの添加物を用いることを禁止しているのではく，ブルガリア菌の菌数をさらに増加させるために増殖促進剤などを補助的に添加することも当然可能である。この場合に，増殖促進剤の添加量は，最終的に得られる発酵乳の重量に対して，０～１重量％，０～０．５重量％，又は０～０．１重量％とすることが好ましい。増殖促進剤の代表例は，ｐＨ緩衝剤であり，その他に特許文献１に記載のオレイン酸や特許文献２に記載のグァバ葉エキスなどが挙げられる。 Moreover, according to the present invention, the number of Bulgarian bacteria contained in fermented milk can be increased only by devising a method for producing a lactic acid bacteria starter. Some Bulgarian bacteria produce functional polysaccharides. Therefore, if the lactic acid bacteria starter obtained according to the present invention is used, fermented milk without a miscellaneous taste containing a large amount of polysaccharides can be produced without using additives such as a growth promoter for lactic acid bacteria. The present invention does not prohibit the use of additives such as growth promoters for lactic acid bacteria, but may additionally add growth promoters or the like to further increase the number of Bulgarian bacteria. Of course it is possible. In this case, the addition amount of the growth promoter should be 0 to 1% by weight, 0 to 0.5% by weight, or 0 to 0.1% by weight with respect to the weight of the finally obtained fermented milk. Is preferred. A typical example of the growth promoter is a pH buffer, and other examples include oleic acid described in Patent Document 1 and guava leaf extract described in Patent Document 2.
　なお，図示は省略するが，発酵乳の製造工程（Ｓ６～Ｓ９）において，原料乳に対して乳糖分解を行うことも可能である。その場合，原料乳調整工程後（Ｓ６）の適切なタイミングで乳糖分解を実施すればよい。 In addition, although illustration is abbreviate | omitted, lactose decomposition | disassembly can also be performed with respect to raw material milk in the manufacturing process (S6-S9) of fermented milk. In that case, lactose decomposition may be performed at an appropriate timing after the raw material milk adjustment step (S6).
　以下，実施例を用いて，本発明を具体的に説明する。ただし，本発明は，以下の実施例に限定されることなく，公知の手法に基づく様々な改良を加えることができるものである。 Hereinafter, the present invention will be described in detail with reference to examples. However, the present invention is not limited to the following examples, and various improvements based on known methods can be added.
＜実施例１：殺菌前の培地を乳糖分解：第１の乳糖分解工程＞
　脱脂粉乳：８０ｇ，水道水：７２０ｇを混合して培地を調製した。この培地を５℃に温度調整し，乳糖分解酵素（ＧＯＤＯ－ＹＮＬ，合同酒精株式会社）を０．１重量％添加した。培地中の乳糖分解率が１００％となった後，９５℃，５分間で加熱（殺菌）した後に，４０℃に冷却した。そして，ブルガリア菌及びサーモフィルス菌を含む乳酸菌を０．１５重量％で接種した後に，発酵室（４０℃）で，乳酸酸度が０．７５％に到達するまで静置発酵してから，冷蔵室（１０℃以下）で冷却して，乳酸菌スターター（実施例１）を製造した。１０℃に達した時点で乳酸菌スターターに含まれるブルガリア菌とサーモフィルス菌の菌数を測定したところ，それぞれ５１．０×１０７cfu/g，７１．０×１０７cfu/gであった。 <Example 1: Lactose decomposition of medium before sterilization: first lactose decomposition step>
Non-fat dry milk: 80 g and tap water: 720 g were mixed to prepare a medium. The temperature of this medium was adjusted to 5 ° C., and lactose-degrading enzyme (GODO-YNL, Godo Sakesei Co., Ltd.) was added at 0.1% by weight. After the lactose decomposition rate in the medium reached 100%, it was heated (sterilized) at 95 ° C. for 5 minutes and then cooled to 40 ° C. And after inoculating 0.15% by weight of lactic acid bacteria including Bulgarian bacteria and Thermophilus bacteria, in a fermentation room (40 ° C.), it is left to stand until the lactic acid acidity reaches 0.75%, and then the refrigerator room. The mixture was cooled at 10 ° C. or lower to produce a lactic acid bacteria starter (Example 1). When the number of Bulgarian and Thermophilus bacteria contained in the lactic acid bacteria starter was measured when the temperature reached 10 ° C., they were 51.0 × 10 7 cfu / g and 71.0 × 10 7 cfu / g, respectively.
　更に，生乳：８００ｇ，脱脂粉乳：２０ｇ，砂糖：４５ｇ，水道水：１００ｇを混合して原料乳を調製し，９５℃，５分間で加熱（殺菌）した後に，４３℃に冷却した。そして，原料乳に上記の乳酸菌スターター（実施例１）を３重量％で接種した後に，原料乳をカップ容器（容量：１００ｇ，プラスチック製）へ充填し，発酵室（４３℃）で，乳酸酸度が０．８％に到達するまで静置発酵してから，冷蔵室（１０℃以下）で冷却して，セットタイプヨーグルト（発酵乳）を製造した。１０℃に達した時点でセットタイプヨーグルトに含まれるブルガリア菌とサーモフィルス菌の菌数を測定したところ，それぞれ４４．５×１０７cfu/g，６７．０×１０７cfu/gであった。 Furthermore, raw milk: 800 g, skim milk powder: 20 g, sugar: 45 g, tap water: 100 g were mixed to prepare raw milk, heated (sterilized) at 95 ° C. for 5 minutes, and then cooled to 43 ° C. Then, after inoculating the raw milk with the above lactic acid bacteria starter (Example 1) at 3% by weight, the raw milk is filled into a cup container (capacity: 100 g, made of plastic), and in the fermentation chamber (43 ° C.) Was allowed to stand and fermented until it reached 0.8%, and then cooled in a refrigerator (10 ° C. or lower) to produce a set-type yogurt (fermented milk). When the number of Bulgarian and Thermophilus bacteria contained in the set-type yogurt was measured when the temperature reached 10 ° C., it was 44.5 × 10 7 cfu / g and 67.0 × 10 7 cfu / g, respectively. .
＜実施例２：殺菌後の培地を乳糖分解：第２の乳糖分解工程＞
　脱脂粉乳：８０ｇ，水道水：７２０ｇを混合して培地を調製した。この培地を９５℃，５分間で加熱（殺菌）した後に，４０℃に冷却し，乳糖分解酵素（ＧＯＤＯ－ＹＮＬ，合同酒精株式会社）を０．１重量％添加した。培地中の乳糖分解率が７０％以上となった後，ブルガリア菌及びサーモフィルス菌を含む乳酸菌を０．１５重量％で接種した。培地を発酵室（４０℃）で，乳酸酸度が０．７５％に到達するまで静置発酵してから，冷蔵室（１０℃以下）で冷却して，乳酸菌スターター（実施例２）を製造した。１０℃に達した時点で乳酸菌スターターに含まれるブルガリア菌とサーモフィルス菌の菌数を測定したところ，それぞれ５８．５×１０７cfu/g，５６．０×１０７cfu/gであった。 <Example 2: Lactose decomposition of medium after sterilization: second lactose decomposition step>
Non-fat dry milk: 80 g and tap water: 720 g were mixed to prepare a medium. The medium was heated (sterilized) at 95 ° C. for 5 minutes, then cooled to 40 ° C., and lactose-degrading enzyme (GODO-YNL, Godo Sakesei Co., Ltd.) was added at 0.1% by weight. After the lactose decomposition rate in the medium reached 70% or more, lactic acid bacteria including Bulgarian bacteria and Thermophilus bacteria were inoculated at 0.15% by weight. The medium was fermented in a fermentation chamber (40 ° C.) until the lactic acid acidity reached 0.75%, and then cooled in a refrigerator (10 ° C. or lower) to produce a lactic acid bacteria starter (Example 2). . When the number of Bulgarian bacteria and Thermophilus bacteria contained in the lactic acid bacteria starter was measured when the temperature reached 10 ° C., they were 58.5 × 10 7 cfu / g and 56.0 × 10 7 cfu / g, respectively.
　更に，生乳：８００ｇ，脱脂粉乳：２０ｇ，砂糖：４５ｇ，水道水：１００ｇを混合して原料乳を調製し，９５℃，５分間で加熱（殺菌）した後に，４３℃に冷却した。そして，原料乳に上記の乳酸菌（実施例２）を３重量％で接種した後に，原料乳をカップ容器（容量：１００ｇ，プラスチック製）へ充填し，発酵室（４３℃）で，乳酸酸度が０．８％に到達するまで静置発酵してから，冷蔵室（１０℃以下）で冷却して，セットタイプヨーグルトを製造した。１０℃に達した時点でセットタイプヨーグルトに含まれるブルガリア菌とサーモフィルス菌の菌数を測定したところ，それぞれ３７．０×１０７cfu/g，６０．０×１０７cfu/gであった。 Furthermore, raw milk: 800 g, skim milk powder: 20 g, sugar: 45 g, tap water: 100 g were mixed to prepare raw milk, heated (sterilized) at 95 ° C. for 5 minutes, and then cooled to 43 ° C. And after inoculating the above-mentioned lactic acid bacteria (Example 2) at 3% by weight into the raw milk, the raw milk is filled into a cup container (capacity: 100 g, made of plastic), and the lactic acid acidity is increased in the fermentation chamber (43 ° C.). After stationary fermentation until it reached 0.8%, it was cooled in a refrigerator (10 ° C. or lower) to produce a set-type yogurt. When the number of Bulgarian and Thermophilus bacteria contained in the set-type yogurt was measured when the temperature reached 10 ° C., they were 37.0 × 10 7 cfu / g and 60.0 × 10 7 cfu / g, respectively. .
＜実施例３：賦活培養と共に培地を乳糖分解：第３の乳糖分解工程＞
　脱脂粉乳：８０ｇ，水道水：７２０ｇを混合して培地を調製した。この培地を９５℃，５分間で加熱（殺菌）した後に，４０℃に冷却し，ブルガリア菌及びサーモフィルス菌を含む乳酸菌を０．１５重量％で接種するのと同時に，乳糖分解酵素（ＧＯＤＯ－ＹＮＬ，合同酒精株式会社）を０．１重量％添加した。培地を発酵室（４０℃）で，乳酸酸度が０．７５％に到達するまで静置発酵してから，冷蔵室（１０℃以下）で冷却して，乳酸菌スターター（実施例３）を製造した。１０℃に達した時点で乳酸菌スターターに含まれるブルガリア菌とサーモフィルス菌の菌数を測定したところ，それぞれ６３．０×１０７cfu/g，４７．０×１０７cfu/gであった。 <Example 3: Lactose decomposition of the medium together with activated culture: third lactose decomposition step>
Non-fat dry milk: 80 g and tap water: 720 g were mixed to prepare a medium. The medium was heated (sterilized) at 95 ° C. for 5 minutes, then cooled to 40 ° C., and lactic acid bacteria including Bulgarian bacteria and Thermophilus bacteria were inoculated at 0.15% by weight. At the same time, lactose-degrading enzyme (GODO- 0.1% by weight of YNL, Godo Shusei Co., Ltd.) was added. The medium was fermented in a fermentation chamber (40 ° C.) until the lactic acid acidity reached 0.75%, and then cooled in a refrigerator (10 ° C. or lower) to produce a lactic acid bacteria starter (Example 3). . When the number of Bulgarian and Thermophilus bacteria contained in the lactic acid bacteria starter was measured when the temperature reached 10 ° C., they were 63.0 × 10 7 cfu / g and 47.0 × 10 7 cfu / g, respectively.
　更に，生乳：８００ｇ，脱脂粉乳：２０ｇ，砂糖：４５ｇ，水道水：１００ｇを混合して原料乳を調製し，９５℃，５分間で加熱（殺菌）した後に，４３℃に冷却した。そして，原料乳に上記の乳酸菌（実施例３）を３重量％で接種した後に，原料乳をカップ容器（容量：１００ｇ，プラスチック製）へ充填し，発酵室（４３℃）で，乳酸酸度が０．８％に到達するまで静置発酵してから，冷蔵室（１０℃以下）で冷却して，セットタイプヨーグルトを製造した。１０℃に達した時点でセットタイプヨーグルトに含まれるブルガリア菌とサーモフィルス菌の菌数を測定したところ，それぞれ５２．５×１０７cfu/g，４０．５×１０７cfu/gであった。 Furthermore, raw milk: 800 g, skim milk powder: 20 g, sugar: 45 g, tap water: 100 g were mixed to prepare raw milk, heated (sterilized) at 95 ° C. for 5 minutes, and then cooled to 43 ° C. And after inoculating the above-mentioned lactic acid bacteria (Example 3) in raw material milk at 3% by weight, the raw material milk is filled into a cup container (capacity: 100 g, made of plastic), and the lactic acid acidity is increased in the fermentation chamber (43 ° C.). After stationary fermentation until it reached 0.8%, it was cooled in a refrigerator (10 ° C. or lower) to produce a set-type yogurt. When the number of Bulgarian and Thermophilus bacteria contained in the set-type yogurt was measured when the temperature reached 10 ° C., it was 52.5 × 10 7 cfu / g and 40.5 × 10 7 cfu / g, respectively. .
＜比較例１：乳糖分解せず＞
　脱脂粉乳：８０ｇ，水道水：７２０ｇを混合して培地を調製した。この培地を９５℃，５分間で加熱（殺菌）した後に，４０℃に冷却し，ブルガリア菌及びサーモフィルス菌を含む乳酸菌を０．１５重量％で接種した。培地を発酵室（４０℃）で，乳酸酸度が０．７５％に到達するまで静置発酵してから，冷蔵室（１０℃以下）で冷却して，乳酸菌スターター（比較例１）を製造した。１０℃に達した時点で乳酸菌スターターに含まれるブルガリア菌とサーモフィルス菌の菌数を測定したところ，それぞれ１８．０×１０７cfu/g，７９．５×１０７cfu/gであった。 <Comparative Example 1: Lactose is not degraded>
Non-fat dry milk: 80 g and tap water: 720 g were mixed to prepare a medium. This medium was heated (sterilized) at 95 ° C. for 5 minutes, then cooled to 40 ° C., and inoculated with 0.15% by weight of lactic acid bacteria including Bulgarian bacteria and Thermophilus bacteria. The medium was fermented in a fermentation chamber (40 ° C.) until the lactic acid acidity reached 0.75%, and then cooled in a refrigerator (10 ° C. or lower) to produce a lactic acid bacteria starter (Comparative Example 1). . When the number of Bulgarian bacteria and Thermophilus bacteria contained in the lactic acid bacteria starter was measured when the temperature reached 10 ° C., they were 18.0 × 10 7 cfu / g and 79.5 × 10 7 cfu / g, respectively.
　更に，生乳：８００ｇ，脱脂粉乳：２０ｇ，砂糖：４５ｇ，水道水：１００ｇを混合して原料乳を調製し，９５℃，５分間で加熱（殺菌）した後に，４３℃に冷却した。そして，原料乳に上記の乳酸菌スターター（比較例１）を３重量％で接種した後に，原料乳をカップ容器（容量：１００ｇ，プラスチック製）へ充填し，発酵室（４３℃）で，乳酸酸度が０．８％に到達するまで静置発酵してから，冷蔵室（１０℃以下）で冷却して，セットタイプヨーグルトを製造した。１０℃に達した時点でセットタイプヨーグルトに含まれるブルガリア菌とサーモフィルス菌の菌数を測定したところ，それぞれ１３．０×１０７cfu/g，９７．５×１０７cfu/gであった。 Furthermore, raw milk: 800 g, skim milk powder: 20 g, sugar: 45 g, tap water: 100 g were mixed to prepare raw milk, heated (sterilized) at 95 ° C. for 5 minutes, and then cooled to 43 ° C. After inoculating the raw milk with the above lactic acid bacteria starter (Comparative Example 1) at 3% by weight, the raw milk is filled into a cup container (capacity: 100 g, made of plastic), and the lactic acid acidity in the fermentation chamber (43 ° C.) Was allowed to stand until it reached 0.8%, and then cooled in a refrigerator (10 ° C. or lower) to produce a set-type yogurt. When the numbers of Bulgarian and Thermofilus contained in the set-type yogurt were measured when the temperature reached 10 ° C., they were 13.0 × 10 7 cfu / g and 97.5 × 10 7 cfu / g, respectively. .
＜考察＞
　上記した実施例１，実施例２，実施例３，及び比較例１におけるブルガリア菌及びサーモフィルス菌の菌数を，以下の表１にまとめて示す。表１に示すとおり，各実施例に従って乳酸菌スターターの培養過程で培地に対して乳糖分解を実施することにより，乳酸菌スターター及びそれを利用して得られた発酵乳（ヨーグルト製品）は，比較例の発酵乳と比較し，ブルガリア菌の菌数が，サーモフィルス菌と比較して相対的に増加している傾向が確認された。 <Discussion>
The numbers of Bulgarian bacteria and Thermophilus bacteria in Examples 1, 2 and 3 and Comparative Example 1 are summarized in Table 1 below. As shown in Table 1, lactic acid bacteria starter and fermented milk (yogurt product) obtained by using lactose decomposition for the medium in the lactic acid bacteria starter culturing process according to each example, Compared to fermented milk, it was confirmed that the number of Bulgarian bacteria was relatively increased compared to Thermophilus.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　表１に示されるように，実施例１の乳酸菌スターターでは，サーモフィルス菌に対するブルガリア菌の菌数比が約７１％となった。また，実施例２の乳酸菌スターターでは，サーモフィルス菌に対するブルガリア菌の菌数比が約１０４％となった。また，実施例３の乳酸菌スターターでは，サーモフィルス菌に対するブルガリア菌の菌数比が約１３４％となった。これに対して，比較例の乳酸菌スターターでは，サーモフィルス菌に対するブルガリア菌の菌数比が約２２％であった。このことから，培地に対して乳糖分解を実施することにより，ブルガリア菌の増殖が促進され，サーモフィルス菌の増殖が抑制されることが確認された。 As shown in Table 1, in the lactic acid bacteria starter of Example 1, the ratio of Bulgarian bacteria to Thermophilus bacteria was about 71%. In addition, in the lactic acid bacteria starter of Example 2, the ratio of Bulgarian bacteria to Thermophilus bacteria was about 104%. Moreover, in the lactic acid bacteria starter of Example 3, the bacterial count ratio of Bulgarian bacteria to Thermophilus bacteria was about 134%. On the other hand, in the lactic acid bacteria starter of the comparative example, the bacterial count ratio of Bulgaria bacteria to Thermophilus bacteria was about 22%. From this, it was confirmed that by carrying out lactose decomposition on the medium, the growth of Bulgarian bacteria was promoted and the growth of Thermophilus was suppressed.
　また，実施例１で得られたヨーグルトでは，サーモフィルス菌に対するブルガリア菌の菌数比が約６６％となった。また，実施例２で得られたヨーグルトでは，サーモフィルス菌に対するブルガリア菌の菌数比が約６１％となった。また，実施例３で得られたヨーグルトでは，サーモフィルス菌に対するブルガリア菌の菌数比が約１２９％となった。これに対して，比較例で得られたヨーグルトでは，サーモフィルス菌に対するブルガリア菌の菌数比が約１３％であった。このことから，培養過程で乳糖分解を実施した乳酸菌スターターを利用してヨーグルトを製造することにより，ブルガリア菌の増殖が促進され，サーモフィルス菌の増殖が抑制されることが確認された。 In addition, in the yogurt obtained in Example 1, the ratio of Bulgarian bacteria to Thermophilus was about 66%. In addition, in the yogurt obtained in Example 2, the ratio of the number of Bulgarian bacteria to that of Thermophilus was about 61%. Moreover, in the yogurt obtained in Example 3, the ratio of the number of Bulgarian bacteria to Thermophilus was about 129%. On the other hand, in the yogurt obtained in the comparative example, the bacterial count ratio of Bulgaria bacteria to Thermophilus was about 13%. From this, it was confirmed that the growth of Bulgarian bacteria was promoted and the growth of Thermophilus bacteria was suppressed by producing yogurt using a lactic acid bacteria starter that had undergone lactose decomposition during the culturing process.
＜実施例４：予め乳糖分解した中和培養スターター＞
　脱脂粉乳：２５０ｇ，乳糖：１８ｇ，酵母エキス：４．５ｇ，乳化剤：０．４５ｇ，水道水：１２２７．５ｇを混合して培地を調製した。この培地を４０℃に温度調整し，乳糖分解酵素（ＧＯＤＯ－ＹＮＬ。合同酒精株式会社）を０．１重量％添加した。培地中の乳糖分解率が１００％となった後，１２１℃，１分間で加熱（殺菌）した後に，３９．５℃に冷却した。そして，ブルガリア菌及びサーモフィルス菌を含む乳酸菌を０．６重量％接種した後に，２５重量％濃度の水酸化ナトリウム溶液を用いてｐＨ＝５．５５に調整しながら，３９．５℃，窒素加圧条件下で９時間中和培養した。培養終了後，１０℃以下に冷却し，一次乳酸菌スターター（実施例４）を製造した。さらに，ここで得られた一次乳酸菌スターターを上記と同じ条件および手順で培養し，二次乳酸菌スターターを製造した。 <Example 4: Neutralized culture starter previously lactose-decomposed>
Non-fat dry milk: 250 g, lactose: 18 g, yeast extract: 4.5 g, emulsifier: 0.45 g, tap water: 1227.5 g were mixed to prepare a medium. The temperature of this medium was adjusted to 40 ° C., and lactose-degrading enzyme (GODO-YNL, Godo Sakesei Co., Ltd.) was added at 0.1% by weight. After the lactose decomposition rate in the medium reached 100%, it was heated (disinfected) at 121 ° C. for 1 minute, and then cooled to 39.5 ° C. Then, after inoculating 0.6% by weight of lactic acid bacteria including Bulgarian bacteria and Thermophilus bacteria, the pH was adjusted to 5.55 using a 25% by weight sodium hydroxide solution while adding nitrogen at 39.5 ° C. The mixture was neutralized for 9 hours under pressure. After completion of the culture, the mixture was cooled to 10 ° C. or lower to produce a primary lactic acid bacteria starter (Example 4). Furthermore, the primary lactic acid bacteria starter obtained here was cultured under the same conditions and procedures as described above to produce a secondary lactic acid bacteria starter.
　更に，生乳：８００ｇ，脱脂粉乳：２０ｇ，砂糖：４５ｇ，水道水：１００ｇを混合して原料乳を調製し，９５℃，５分間で加熱（殺菌）した後に，４３℃に冷却した。そして，原料乳に上記の二次乳酸菌スターターを０．１５重量％で接種した後に，原料乳をカップ容器（容量：１００ｇ，プラスチック製）へ充填し，発酵室（４３℃）で，乳酸酸度が０．８％に到達するまで静置発酵してから，冷蔵室（１０℃以下）で冷却して，セットタイプヨーグルト（発酵乳）を製造した。 Furthermore, raw milk: 800 g, skim milk powder: 20 g, sugar: 45 g, tap water: 100 g were mixed to prepare raw milk, heated (sterilized) at 95 ° C. for 5 minutes, and then cooled to 43 ° C. And after inoculating the above-mentioned secondary lactic acid bacteria starter at 0.15% by weight into raw milk, the raw milk is filled into a cup container (capacity: 100 g, made of plastic), and the lactic acid acidity is increased in the fermentation chamber (43 ° C.). After stationary fermentation until it reached 0.8%, it was cooled in a refrigerator (10 ° C. or lower) to produce a set type yogurt (fermented milk).
＜比較例２：乳糖分解しない中和培養スターター＞
　脱脂粉乳：２５０ｇ，乳糖：１８ｇ，酵母エキス：４．５ｇ，乳化剤：０．４５ｇ，水道水：１２２７．５ｇを混合して培地を調製した。この培地を１２１℃，１分間で加熱（殺菌）した後に，３９．５℃に冷却した。そして，ブルガリア菌及びサーモフィルス菌を含む乳酸菌を０．６重量％接種した後に，２５重量％濃度の水酸化ナトリウム溶液を用いてｐＨ＝５．５５に調整しながら，３９．５℃，窒素加圧条件下で９時間中和培養した。培養終了後，１０℃以下に冷却し，一次乳酸菌スターター（比較例２）を製造した。さらに，ここで得られた一次乳酸菌スターターを上記と同じ条件および手順で培養し，二次乳酸菌スターターを製造した。 <Comparative Example 2: Neutralization culture starter that does not decompose lactose>
Non-fat dry milk: 250 g, lactose: 18 g, yeast extract: 4.5 g, emulsifier: 0.45 g, tap water: 1227.5 g were mixed to prepare a medium. The medium was heated (sterilized) at 121 ° C. for 1 minute and then cooled to 39.5 ° C. Then, after inoculating 0.6% by weight of lactic acid bacteria including Bulgarian bacteria and Thermophilus bacteria, the pH was adjusted to 5.55 using a 25% by weight sodium hydroxide solution while adding nitrogen at 39.5 ° C. The mixture was neutralized for 9 hours under pressure. After completion of the culture, the mixture was cooled to 10 ° C. or lower to produce a primary lactic acid bacteria starter (Comparative Example 2). Furthermore, the primary lactic acid bacteria starter obtained here was cultured under the same conditions and procedures as described above to produce a secondary lactic acid bacteria starter.
　更に，生乳：８００ｇ，脱脂粉乳：２０ｇ，砂糖：４５ｇ，水道水：１００ｇを混合して原料乳を調製し，９５℃，５分間で加熱（殺菌）した後に，４３℃に冷却した。そして，原料乳に上記の二次乳酸菌スターターを０．１５重量％で接種した後に，原料乳をカップ容器（容量：１００ｇ，プラスチック製）へ充填し，発酵室（４３℃）で，乳酸酸度が０．８％に到達するまで静置発酵してから，冷蔵室（１０℃以下）で冷却して，セットタイプヨーグルト（発酵乳）を製造した。 Furthermore, raw milk: 800 g, skim milk powder: 20 g, sugar: 45 g, tap water: 100 g were mixed to prepare raw milk, heated (sterilized) at 95 ° C. for 5 minutes, and then cooled to 43 ° C. And after inoculating the above-mentioned secondary lactic acid bacteria starter at 0.15% by weight into raw milk, the raw milk is filled into a cup container (capacity: 100 g, made of plastic), and the lactic acid acidity is increased in the fermentation chamber (43 ° C.). After stationary fermentation until it reached 0.8%, it was cooled in a refrigerator (10 ° C. or lower) to produce a set type yogurt (fermented milk).
＜考察＞
　上記した実施例４及び比較例２におけるブルガリア菌及びサーモフィルス菌の菌数を，以下の表２に示す。表２に示すとおり，中和培養スターターにおいても，各実施例に従ってその培養過程で培地に対して乳糖分解を実施することにより，乳酸菌スターター及びそれを利用して得られた発酵乳（ヨーグルト製品）は，比較例の発酵乳と比較し，ブルガリア菌の菌数が，サーモフィルス菌と比較して相対的に増加している傾向が確認された。また，表２に示されるように，本発明により得られた乳酸菌スターターは，比較例と比較したときに，何度継代しても（植え継いでも），ブルガリア菌の菌数がサーモフィルス菌に対して増加傾向にあるという本発明の効果が現れることが確認された。 <Discussion>
The numbers of Bulgarian bacteria and Thermophilus bacteria in Example 4 and Comparative Example 2 described above are shown in Table 2 below. As shown in Table 2, also in the neutralization culture starter, by carrying out lactose decomposition on the medium in the culture process according to each example, lactic acid bacteria starter and fermented milk obtained using the same (yogurt product) Compared with the fermented milk of the comparative example, it was confirmed that the number of Bulgarian bacteria was relatively increased compared to Thermophilus. In addition, as shown in Table 2, the lactic acid bacteria starter obtained by the present invention has the same number of Bulgarian bacteria as Thermophilus, regardless of how many times it is passaged (planted) as compared with the comparative example. It was confirmed that the effect of the present invention that it is in an increasing tendency appears.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
＜実施例５：殺菌前の培地を乳糖分解＞
　脱脂粉乳：８０ｇ，水道水：７２０ｇを混合して培地を調製した。この原料乳を５℃に温度調整し，乳糖分解酵素（ＧＯＤＯ－ＹＮＬ，合同酒精株式会社）を０．１重量％添加した。原料乳中の乳糖分解率が８０％以上となった後，９５℃，５分間で加熱（殺菌）した後に，４０℃に　冷却した。そして，ブルガリア菌及びサーモフィルス菌を含む乳酸菌を０．１５重量％で接種した後に発酵室（４０℃）で，乳酸酸度が０．７５％に到達するまで静置発酵してから，冷蔵室（１０　℃以下）で冷却して，乳酸菌スターター（実施例５）を製造した。１０℃に達した時点で乳酸菌スターターに含まれるブルガリア菌とサーモフィルス菌の菌数を測定したところ，それぞれ６７．０×１０７cfu/g，６８．０×１０７cfu/gであった。また，乳酸菌スターターにおけるＥＰＳ濃度（菌体外多糖の濃度）を測定したところ，７７．７ｍｇ／ｋｇであった。 <Example 5: Lactose decomposition of medium before sterilization>
Non-fat dry milk: 80 g and tap water: 720 g were mixed to prepare a medium. The temperature of the raw milk was adjusted to 5 ° C., and lactose-degrading enzyme (GODO-YNL, Godo Sakesei Co., Ltd.) was added at 0.1% by weight. After the lactose decomposition rate in the raw milk reached 80% or higher, it was heated (sterilized) at 95 ° C for 5 minutes and then cooled to 40 ° C. And after inoculating lactic acid bacteria containing Bulgaria bacteria and thermophilus bacteria at 0.15% by weight, in a fermentation room (40 ° C.), after standing still until the lactic acid acidity reaches 0.75%, the refrigerator room ( The lactic acid bacteria starter (Example 5) was manufactured by cooling at 10 ° C. or lower. When the numbers of Bulgarian bacteria and Thermophilus bacteria contained in the lactic acid bacteria starter were measured when the temperature reached 10 ° C., they were 67.0 × 10 7 cfu / g and 68.0 × 10 7 cfu / g, respectively. Further, the EPS concentration (extracellular polysaccharide concentration) in the lactic acid bacteria starter was measured and found to be 77.7 mg / kg.
　更に，生乳：８００ｇ，脱脂粉乳：２０ｇ，砂糖：４５ｇ，水道水：１００ｇを混合して，原料乳を調製し，９５℃，５分間で加熱（殺菌）した後に，４３℃に冷却した。そして，上記の乳酸菌スターター（実施例５）を３重量％で接種した後にカップ容器（容量：１００ｇ，プラスチック製）へ充填し，発酵室（４３℃）で，乳酸酸度が０．８％に到達するまで静置発酵してから，冷蔵室（１０℃以下）で冷却して，セットタイプヨーグルト（発酵乳）を製造した。１０℃に達した時点でセットタイプヨーグルトに含まれるブルガリア菌とサーモフィルス菌の菌数を測定したところ，それぞれ３７．０×１０７cfu/g，６０．０×１０７cfu/gであった。また，セットタイプヨーグルトにおけるＥＰＳ濃度を測定したところ，４３．８ｍｇ／ｋｇであった。 Furthermore, raw milk: 800 g, skim milk powder: 20 g, sugar: 45 g, tap water: 100 g were mixed to prepare raw milk, heated (sterilized) at 95 ° C. for 5 minutes, and then cooled to 43 ° C. The lactic acid bacteria starter (Example 5) was inoculated at 3% by weight and then filled into a cup container (capacity: 100 g, made of plastic), and the lactic acid acidity reached 0.8% in the fermentation chamber (43 ° C.). Then, the mixture was allowed to stand for fermentation, and then cooled in a refrigerator (10 ° C. or lower) to produce a set type yogurt (fermented milk). When the number of Bulgarian and Thermophilus bacteria contained in the set-type yogurt was measured when the temperature reached 10 ° C., they were 37.0 × 10 7 cfu / g and 60.0 × 10 7 cfu / g, respectively. . Moreover, when the EPS density | concentration in set type yogurt was measured, it was 43.8 mg / kg.
＜比較例３：乳糖分解せず＞
　脱脂粉乳：８０ｇ，水道水：７２０ｇを混合して培地を調製した。この原料乳を９５℃，５分間で加熱（殺菌）した後に，４０℃に冷却し，ブルガリア菌及びサーモフィルス菌を含む乳酸菌を０．１５重量％で接種した。発酵室（４０℃）で，乳酸酸度が０．７５％に到達するまで静置発酵してから，冷蔵室（１０℃以下）で冷却して，乳酸菌スターター（比較例３）を製造した。１０℃に達した時点で乳酸菌スターターに含まれるブルガリア菌とサーモフィルス菌の菌数を測定したところ，それぞれ１８．０×１０７cfu/g，８０．０×１０７cfu/gであった。また，乳酸菌スターターにおけるＥＰＳ濃度を測定したところ，３８．４ｍｇ／ｋｇであった。 <Comparative Example 3: Lactose is not degraded>
Non-fat dry milk: 80 g and tap water: 720 g were mixed to prepare a medium. The raw milk was heated (sterilized) at 95 ° C. for 5 minutes, cooled to 40 ° C., and inoculated with 0.15% by weight of lactic acid bacteria including Bulgarian bacteria and Thermofilus bacteria. In the fermentation chamber (40 ° C.), the fermentation was allowed to stand until the lactic acid acidity reached 0.75%, and then cooled in the refrigerator (10 ° C. or lower) to produce a lactic acid bacteria starter (Comparative Example 3). When the number of Bulgarian bacteria and Thermophilus bacteria contained in the lactic acid bacteria starter was measured when the temperature reached 10 ° C., they were 18.0 × 10 7 cfu / g and 80.0 × 10 7 cfu / g, respectively. Moreover, when the EPS density | concentration in a lactic acid bacteria starter was measured, it was 38.4 mg / kg.
　更に，生乳：８００ｇ，脱脂粉乳：２０ｇ，砂糖：４５ｇ，水道水：１００ｇを混合して，原料乳を調製し，９５℃，５分間で加熱（殺菌）した後に，４３℃に冷却した。そして，上記の乳酸菌スターター（比較例３）を３重量％で接種した後にカップ容器（容量：１００ｇ，プラスチック製）へ充填し，発酵室（４３℃）で，乳酸酸度が０．８％に到達するまで静置発酵してから，冷蔵室（１０℃以下）で冷却して，セットタイプヨーグルト（発酵乳）を製造した。１０℃に達した時点でセットタイプヨーグルトに含まれるブルガリア菌とサーモフィルス菌の菌数を測定したところ，それぞれ１３．０×１０７cfu/g，９８．０×１０７cfu/gであった。また，セットタイプヨーグルトにおけるＥＰＳ濃度を測定したところ，３０．４ｍｇ／ｋｇであった。 Furthermore, raw milk: 800 g, skim milk powder: 20 g, sugar: 45 g, tap water: 100 g were mixed to prepare raw milk, heated (sterilized) at 95 ° C. for 5 minutes, and then cooled to 43 ° C. Then, after inoculating the above lactic acid bacteria starter (Comparative Example 3) at 3% by weight, it was filled into a cup container (capacity: 100 g, made of plastic), and the lactic acid acidity reached 0.8% in the fermentation chamber (43 ° C.). Then, the mixture was allowed to stand for fermentation, and then cooled in a refrigerator (10 ° C. or lower) to produce a set type yogurt (fermented milk). When the number of Bulgarian and Thermophilus bacteria contained in the set-type yogurt was measured when the temperature reached 10 ° C., it was 13.0 × 10 7 cfu / g and 98.0 × 10 7 cfu / g, respectively. . Moreover, it was 30.4 mg / kg when the EPS density | concentration in set type yogurt was measured.
＜考察＞
　上記した実施例５及び比較例１におけるブルガリア菌の菌数，サーモフィルス菌の菌数，及びＥＰＳ濃度を，以下の表３にまとめて示す。表３に示すとおり，実施例５に従って乳酸菌スターターの培養過程で培地に対して乳糖分解を実施することにより，乳酸菌スターター及びそれを利用して得られた発酵乳（ヨーグルト製品）は，比較例３の発酵乳と比較し，ブルガリア菌の菌数が，サーモフィルス菌と比較して相対的に増加している傾向が確認された。さらに，実施例５では，乳酸菌スターター及びセットタイプヨーグルトの各段階においてＥＰＳ濃度が比較例３を上回ることが確認された。 <Discussion>
Table 3 below collectively shows the number of Bulgarian bacteria, the number of Thermophilus bacteria, and the EPS concentration in Example 5 and Comparative Example 1 described above. As shown in Table 3, the lactobacillus starter and fermented milk (yogurt product) obtained using the lactose bacteria starter and the fermented milk (yogurt product) obtained by carrying out lactose decomposition on the medium in the lactic acid bacteria starter culture process according to Example 5 Compared with fermented milk, the number of Bulgarian bacteria was relatively increased compared to Thermofilus. Further, in Example 5, it was confirmed that the EPS concentration exceeded that of Comparative Example 3 at each stage of the lactic acid bacteria starter and the set type yogurt.
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
　以上，本願明細書では，本発明の内容を表現するために，図面を参照しながら本発明の実施形態及びその実施例の説明を行った。ただし，本発明は，上記実施形態に限定されるものではなく，本願明細書に記載された事項に基づいて当業者が自明な変更形態や改良形態を包含するものである。 As mentioned above, in this specification, in order to express the content of the present invention, the embodiment of the present invention and the example were described, referring to drawings. However, the present invention is not limited to the above-described embodiments, but includes modifications and improvements obvious to those skilled in the art based on the matters described in the present specification.
　本発明は，乳酸菌スターターの製造方法及び発酵乳の製造方法に関する，従って，本発明は，ヨーグルトなどの発酵乳の製造業において好適に利用しうる。 The present invention relates to a method for producing a lactic acid bacteria starter and a method for producing fermented milk. Therefore, the present invention can be suitably used in the manufacturing industry of fermented milk such as yogurt.

Claims (7)

  1. 　原料乳を発酵させて発酵乳を得るのに利用される乳酸菌スターターの製造方法であって，
    　乳成分を含む培地を調製する培地調製工程と，
    　前記培地を殺菌する培地殺菌工程と，
    　殺菌後の前記培地にブルガリア菌を含む乳酸菌を接種する乳酸菌接種工程と，
    　前記乳酸菌接種後の前記培地を発酵させる培地発酵工程と，を含み，
    　前記培地発酵工程よりも前に，前記培地内の乳糖を分解する乳糖分解工程をさらに含む
    　乳酸菌スターターの製造方法。     A method for producing a lactic acid bacteria starter used for fermenting raw milk to obtain fermented milk,
    A medium preparation step for preparing a medium containing milk components;
    A medium sterilization step for sterilizing the medium;
    Lactic acid bacteria inoculation step of inoculating lactic acid bacteria containing Bulgaria bacteria into the medium after sterilization,
    A medium fermentation step of fermenting the medium after inoculation with the lactic acid bacteria,
    A method for producing a lactic acid bacteria starter further comprising a lactose decomposition step of decomposing lactose in the medium prior to the medium fermentation step.
  2. 　前記乳糖分解工程は，前記培地殺菌工程の前に行われる
    　請求項１に記載の乳酸菌スターターの製造方法。     The method for producing a lactic acid bacteria starter according to claim 1, wherein the lactose decomposition step is performed before the medium sterilization step.
  3. 　前記乳糖分解工程は，前記培地殺菌工程後，前記乳酸菌接種工程の前に行われる
    　請求項１に記載の乳酸菌スターターの製造方法。     The method for producing a lactic acid bacteria starter according to claim 1, wherein the lactose decomposition step is performed after the medium sterilization step and before the lactic acid bacteria inoculation step.
  4. 　前記乳糖分解工程は，前記培地に前記乳酸菌と同時に乳糖分解酵素を添加するか，或いは前記乳酸菌接種後の前記培地を発酵温度域に昇温する前に前記培地に乳糖分解酵素を添加することによって，前記培地内の乳糖を分解する工程である
    　請求項１に記載の乳酸菌スターターの製造方法。     In the lactose decomposition step, lactose-degrading enzyme is added to the medium simultaneously with the lactic acid bacteria, or lactose-degrading enzyme is added to the medium before raising the temperature of the medium after inoculation of the lactic acid bacteria to the fermentation temperature range. The method for producing a lactic acid bacteria starter according to claim 1, wherein the lactose in the medium is decomposed.
  5. 　前記乳酸菌は，サーモフィルス菌をさらに含む
    　請求項１に記載の乳酸菌スターターの製造方法。     The method for producing a lactic acid bacteria starter according to claim 1, wherein the lactic acid bacteria further include Thermophilus bacteria.
  6. 　前記乳糖分解工程は，前記培地内の乳糖分解率を７０％以上とする工程である
    　請求項１に記載の乳酸菌スターターの製造方法。     The method for producing a lactic acid bacterium starter according to claim 1, wherein the lactose decomposition step is a step in which a lactose decomposition rate in the medium is 70% or more.
  7. 　請求項１に記載の製造方法により得られた乳酸菌スターターを利用して発酵乳を製造する方法。 A method for producing fermented milk using the lactic acid bacteria starter obtained by the production method according to claim 1.
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